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Changing the folder structure will cause too many broken links for external references (from other sites). So, let's put the content back where it was before the reorg, and instead use the new persona-based navigation to point to documents in the original locations. Also, introduce redirects for some documents that no longer exits. Signed-off-by: David B. Kinder <david.b.kinder@intel.com>
661 lines
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ReStructuredText
661 lines
20 KiB
ReStructuredText
.. _kernel-parameters:
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ACRN Kernel Parameters
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######################
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Generic kernel parameters
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*************************
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A number of kernel parameters control the behavior of ACRN-based systems. Some
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are applicable to the Service OS (SOS) kernel, others to the User OS (UOS)
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kernel, and some are applicable to both.
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This section focuses on generic parameters from the Linux kernel which are
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relevant for configuring or debugging ACRN-based systems.
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.. list-table::
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:header-rows: 1
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:widths: 10,10,50,30
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* - Parameter
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- Used in SOS or UOS
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- Description
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- Usage example
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* - module_blacklist
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- SOS
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- A comma-separated list of modules that should not be loaded.
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Useful to debug or work
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around issues related to specific modules.
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- ::
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module_blacklist=dwc3_pci
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* - no_timer_check
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- SOS,UOS
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- Disables the code which tests for broken timer IRQ sources.
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- ::
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no_timer_check
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* - console
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- SOS,UOS
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- Output console device and options.
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``tty<n>``
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Use the virtual console device <n>.
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``ttyS<n>[,options]``
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Use the specified serial port and options. Default options are
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``9600n8`` meaning 9600 baud, no parity, 8 bits. Options are of the form *bbbbpnf*,
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where:
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| *bbbb* is baud rate, for example 9600;
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| *p* is parity, one of ``n``, ``o``, or ``e`` (for none, odd, or even),
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| *n* is number of bits (typically 8),
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| *f* is flow control (``r`` for RTS, or left blank)
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``hvc<n>``
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Use the hypervisor console device <n>. (This is for both Xen and
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PowerPC hypervisors.)
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- ::
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console=tty0
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console=ttyS0
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console=hvc0
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* - loglevel
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- SOS
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- All Kernel messages with a loglevel less than the console loglevel will
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be printed to the console. The loglevel can also be changed with
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``klogd`` or other programs. The loglevels are defined as follows:
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.. list-table::
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:header-rows: 1
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* - loglevel value
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- Definition
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* - 0 (KERN_EMERG)
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- system is unusable
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* - 1 (KERN_ALERT)
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- action must be taken immediately
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* - 2 (KERN_CRIT)
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- critical conditions
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* - 3 (KERN_ERR)
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- error conditions
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* - 4 (KERN_WARNING)
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- warning conditions
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* - 5 (KERN_NOTICE)
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- normal but significant condition
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* - 6 (KERN_INFO)
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- informational
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* - 7 (KERN_DEBUG)
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- debug-level messages
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- ::
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loglevel=7
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* - ignore_loglevel
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- UOS
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- Ignoring loglevel setting will print **all**
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kernel messages to the console. Useful for debugging.
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We also add it as printk module parameter, so users
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could change it dynamically, usually by changing
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``/sys/module/printk/parameters/ignore_loglevel``.
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- ::
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ignore_loglevel
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* - log_buf_len
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- UOS
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- Sets the size of the printk ring buffer,
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in bytes. n must be a power of two and greater
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than the minimal size. The minimal size is defined
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by LOG_BUF_SHIFT kernel config parameter. There is
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also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
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that allows to increase the default size depending on
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the number of CPUs. See init/Kconfig for more details."
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- ::
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log_buf_len=16M
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* - consoleblank
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- SOS,UOS
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- The console blank (screen saver) timeout in
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seconds. Defaults to 600 (10 minutes). A value of 0
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disables the blank timer.
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- ::
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consoleblank=0
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* - rootwait
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- SOS,UOS
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- Wait (indefinitely) for root device to show up.
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Useful for devices that are detected asynchronously
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(e.g. USB and MMC devices).
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- ::
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rootwait
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* - root
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- SOS,UOS
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- Define the root filesystem
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``/dev/<disk_name><decimal>``
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represents the device number of the partition - device
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number of disk plus the partition number
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``/dev/<disk_name>p<decimal>``
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same as above, this form is used when disk name of
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the partitioned disk ends with a digit. To separate
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disk name and partition slot, a 'p' is inserted.
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``PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF``
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representing the unique id of a partition if the
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partition table provides it. The UUID may be either
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an EFI/GPT UUID, or refer to an MSDOS
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partition using the format SSSSSSSS-PP, where SSSSSSSS is a
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zero-filled hexadecimal representation of the 32-bit
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"NT disk signature", and PP is a zero-filled hexadecimal
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representation of the 1-based partition number.
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- ::
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root=/dev/mmcblk0p1
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root=/dev/vda2
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root=PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF
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* - rw
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- SOS,UOS
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- Mount root device read-write on boot
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- ::
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rw
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* - tsc
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- UOS
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- Disable clocksource stability checks for TSC.
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Format: <string>, where the only supported value is:
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``reliable``:
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Mark TSC clocksource as reliable, and disables clocksource
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verification at runtime, and the stability checks done at bootup.
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Used to enable high-resolution timer mode on older hardware, and in
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virtualized environments.
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- ::
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tsc=reliable
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* - cma
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- SOS
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- Sets the size of the kernel global memory area for
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contiguous memory allocations, and optionally the
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placement constraint by the physical address range of
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memory allocations. A value of 0 disables CMA
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altogether. For more information, see
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``include/linux/dma-contiguous``.
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- ::
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cma=64M@0
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* - hvlog
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- SOS
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- Reserve memory for the ACRN hypervisor log. The reserved space should not
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overlap any other blocks (e.g. hypervisor's reserved space).
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- ::
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hvlog=2M@0x6de00000
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* - memmap
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- SOS
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- Mark specific memory as reserved.
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``memmap=nn[KMG]$ss[KMG]``
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Region of memory to be reserved is from ``ss`` to ``ss+nn``,
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using ``K``, ``M``, and ``G`` representing Kilobytes, Megabytes, and
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Gigabytes, respectively.
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- ::
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memmap=0x400000$0x6da00000
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* - ramoops.mem_address
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ramoops.mem_size
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ramoops.console_size
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- SOS
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- Ramoops is an oops/panic logger that writes its logs to RAM
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before the system crashes. Ramoops uses a predefined memory area
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to store the dump. See `Linux Kernel Ramoops oops/panic logger
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<https://www.kernel.org/doc/html/v4.19/admin-guide/ramoops.html#ramoops-oops-panic-logger>`_
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for details.
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- ::
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ramoops.mem_address=0x6da00000
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ramoops.mem_size=0x400000
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ramoops.console_size=0x200000
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* - reboot_panic
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- SOS
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- Reboot in case of panic
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The comma-delimited parameters are:
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reboot_mode:
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``w`` (warm), ``s`` (soft), ``c`` (cold), or ``g`` (gpio)
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reboot_type:
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``b`` (bios), ``a`` (acpi), ``k`` (kbd), ``t`` (triple), ``e`` (efi),
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or ``p`` (pci)
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reboot_cpu:
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``s###`` (smp, and processor number to be used for rebooting)
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reboot_force:
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``f`` (force), or not specified.
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- ::
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reboot_panic=p,w
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* - maxcpus
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- UOS
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- Maximum number of processors that an SMP kernel
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will bring up during bootup.
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``maxcpus=n`` where n >= 0 limits
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the kernel to bring up ``n`` processors during system bootup.
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Giving n=0 is a special case, equivalent to ``nosmp``,which
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also disables the I/O APIC.
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After bootup, you can bring up additional plugged CPUs by executing
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``echo 1 > /sys/devices/system/cpu/cpuX/online``
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- ::
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maxcpus=1
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* - nohpet
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- UOS
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- Don't use the HPET timer
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- ::
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nohpet
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* - intel_iommu
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- UOS
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- Intel IOMMU driver (DMAR) option
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``on``:
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Enable intel iommu driver.
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``off``:
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Disable intel iommu driver.
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``igfx_off``:
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By default, gfx is mapped as normal device. If a gfx
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device has a dedicated DMAR unit, the DMAR unit is
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bypassed by not enabling DMAR with this option. In
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this case, gfx device will use physical address for DMA.
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- ::
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intel_iommu=off
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Intel GVT-g (AcrnGT) Parameters
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*******************************
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This table gives an overview of all the Intel GVT-g parameters that are
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available to tweak the behavior of the graphics sharing (Intel GVT-g, aka
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AcrnGT) capabilities in ACRN. The `GVT-g-kernel-options`_
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section below has more details on a few select parameters.
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.. list-table::
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:header-rows: 1
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:widths: 10,10,50,30
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* - Parameter
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- Used in SOS or UOS
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- Description
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- Usage example
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* - i915.enable_gvt
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- SOS
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- Enable Intel GVT-g graphics virtualization support in the host
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- ::
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i915.enable_gvt=1
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* - i915.enable_pvmmio
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- SOS, UOS
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- Control Para-Virtualized MMIO (PVMMIO). It batches sequential MMIO writes
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into a shared buffer between the SOS and UOS
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- ::
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i915.enable_pvmmio=0x1F
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* - i915.gvt_workload_priority
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- SOS
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- Define the priority level of UOS graphics workloads
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- ::
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i915.gvt_workload_priority=1
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* - i915.enable_initial_modeset
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- SOS
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- On MRB, value must be ``1``. On NUC or UP2 boards, value must be
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``0``. See :ref:`i915-enable-initial-modeset`.
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- ::
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i915.enable_initial_modeset=1
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i915.enable_initial_modeset=0
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* - i915.nuclear_pageflip
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- SOS,UOS
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- Force enable atomic functionality on platforms that don't have full support yet.
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- ::
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i915.nuclear_pageflip=1
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* - i915.avail_planes_per_pipe
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- SOS
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- See :ref:`i915-avail-planes-owners`.
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- ::
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i915.avail_planes_per_pipe=0x01010F
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* - i915.domain_plane_owners
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- SOS
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- See :ref:`i915-avail-planes-owners`.
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- ::
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i915.domain_plane_owners=0x011111110000
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* - i915.domain_scaler_owner
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- SOS
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- See `i915.domain_scaler_owner`_
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- ::
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i915.domain_scaler_owner=0x021100
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* - i915.enable_guc
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- SOS
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- Enable GuC load for HuC load.
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- ::
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i915.enable_guc=0x02
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* - i915.avail_planes_per_pipe
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- UOS
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- See :ref:`i915-avail-planes-owners`.
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- ::
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i915.avail_planes_per_pipe=0x070F00
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* - i915.enable_guc
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- UOS
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- Disable GuC
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- ::
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i915.enable_guc=0
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* - i915.enable_hangcheck
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- UOS
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- Disable check GPU activity for detecting hangs.
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- ::
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i915.enable_hangcheck=0
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* - i915.enable_fbc
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- UOS
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- Enable frame buffer compression for power savings
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- ::
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i915.enable_fbc=1
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.. _GVT-g-kernel-options:
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GVT-g (AcrnGT) Kernel Options details
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=====================================
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This section provides additional information and details on the kernel command
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line options that are related to AcrnGT.
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i915.enable_gvt
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---------------
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This option enables support for Intel GVT-g graphics virtualization
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support in the host. By default, it's not enabled, so we need to add
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``i915.enable_gvt=1`` in the SOS kernel command line. This is a Service
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OS only parameter, and cannot be enabled in the User OS.
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i915.enable_pvmmio
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------------------
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We introduce the feature named **Para-Virtualized MMIO** (PVMMIO)
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to improve graphics performance of the GVT-g guest.
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This feature batches sequential MMIO writes into a
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shared buffer between the Service OS and User OS, and then submits a
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para-virtualized command to notify to GVT-g in Service OS. This
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effectively reduces the trap numbers of MMIO operations and improves
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overall graphics performance.
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The ``i915.enable_pvmmio`` option controls
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the optimization levels of the PVMMIO feature: each bit represents a
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sub-feature of the optimization. By default, all
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sub-features of PVMMIO are enabled. They can also be selectively
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enabled or disabled..
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The PVMMIO optimization levels are:
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* PVMMIO_ELSP_SUBMIT = 0x1 - Batch submission of the guest graphics
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workloads
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* PVMMIO_PLANE_UPDATE = 0x2 - Batch plane register update operations
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* PVMMIO_PLANE_WM_UPDATE = 0x4 - Batch watermark registers update operations
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* PVMMIO_MASTER_IRQ = 0x8 - Batch IRQ related registers
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* PVMMIO_PPGTT_UPDATE = 0x10 - Use PVMMIO method to update the PPGTT table
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of guest.
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.. note:: This parameter works in both the Service OS and User OS, but
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changes to one will affect the other. For example, if either SOS or UOS
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disables the PVMMIO_PPGTT_UPDATE feature, this optimization will be
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disabled for both.
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i915.gvt_workload_priority
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--------------------------
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AcrnGT supports **Prioritized Rendering** as described in the
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:ref:`GVT-g-prioritized-rendering` high-level design. This
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configuration option controls the priority level of GVT-g guests.
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Priority levels range from -1023 to 1023.
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The default priority is zero, the same priority as the Service OS. If
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the level is less than zero, the guest's priority will be lower than the
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Service OS, so graphics preemption will work and the prioritized
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rendering feature will be enabled. If the level is greater than zero,
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UOS graphics workloads will preempt most of the SOS graphics workloads,
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except for display updating related workloads that use a default highest
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priority (1023).
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Currently, all UOSes share the same priority.
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This is a Service OS only parameters, and does
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not work in the User OS.
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.. _i915-enable-initial-modeset:
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i915.enable_initial_modeset
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---------------------------
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At time, kernel graphics must be initialized with a valid display
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configuration with full display pipeline programming in place before the
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user space is initialized and without a fbdev & fb console.
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When ``i915.enable_initial_modeset=1``, the FBDEV of i915 will not be
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initialized, so users would not be able to see the fb console on screen.
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If there is no graphics UI running by default, users will see black
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screens displayed.
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When ``i915.enable_initial_modeset=0`` in SOS, the plane restriction
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(also known as plane-based domain ownership) feature will be disabled.
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(See the next section and :ref:`plane_restriction` in the ACRN GVT-g
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High Level Design for more information about this feature.)
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In the current configuration, we will set
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``i915.enable_initial_modeset=1`` in SOS and
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``i915.enable_initial_modeset=0`` in UOS.
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This parameter is not used on UEFI platforms.
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.. _i915-avail-planes-owners:
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i915.avail_planes_per_pipe and i915.domain_plane_owners
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-------------------------------------------------------
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Both Service OS and User OS are provided a set of HW planes where they
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can display their contents. Since each domain provides its content,
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there is no need for any extra composition to be done through SOS.
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``i915.avail_planes_per_pipe`` and ``i915.domain_plane_owners`` work
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together to provide the plane restriction (or plan-based domain
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ownership) feature.
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* i915.domain_plane_owners
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On Intel's display hardware, each pipeline contains several planes, which are
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blended
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together by their Z-order and rendered to the display monitors. In
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AcrnGT, we can control each planes' ownership so that the domains can
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display contents on the planes they own.
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The ``i915.domain_plane_owners`` parameter controls the ownership of all
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the planes in the system, as shown in :numref:`i915-planes-pipes`. Each
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4-bit nibble identifies the domain id owner for that plane and a group
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of 4 nibbles represents a pipe. This is a Service OS only configuration
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and cannot be modified at runtime. Domain ID 0x0 is for the Service OS,
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the User OS use domain IDs from 0x1 to 0xF.
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.. figure:: images/i915-image1.png
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:width: 900px
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:align: center
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:name: i915-planes-pipes
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i915.domain_plane_owners
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For example, if we set ``i915.domain_plane_owners=0x010001101110``, the
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plane ownership will be as shown in :numref:`i915-planes-example1` - SOS
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(green) owns plane 1A, 1B, 4B, 1C, and 2C, and UOS #1 owns plane 2A, 3A,
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4A, 2B, 3B and 3C.
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.. figure:: images/i915-image2.png
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:width: 900px
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:align: center
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:name: i915-planes-example1
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i915.domain_plane_owners example
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Some other examples:
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* i915.domain_plane_owners=0x022211110000 - SOS (0x0) owns planes on pipe A;
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UOS #1 (0x1) owns all planes on pipe B; and UOS #2 (0x2) owns all
|
|
planes on pipe C (since, in the representation in
|
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:numref:`i915-planes-pipes` above, there are only 3 planes attached to
|
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pipe C).
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* i915.domain_plane_owners=0x000001110000 - SOS owns all planes on pipe A
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and pipe C; UOS #1 owns plane 1, 2 and 3 on pipe B. Plane 4 on pipe B
|
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is owned by the SOS so that if it wants to display notice message, it
|
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can display on top of the UOS.
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|
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* i915.avail_planes_per_pipe
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Option ``i915.avail_planes_per_pipe`` is a bitmask (shown in
|
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:numref:`i915-avail-planes`) that tells the i915
|
|
driver which planes are available and can be exposed to the compositor.
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This is a parameter that must to be set in each domain. If
|
|
``i915.avail_planes_per_pipe=0``, the plane restriction feature is disabled.
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|
|
.. figure:: images/i915-image3.png
|
|
:width: 600px
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:align: center
|
|
:name: i915-avail-planes
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|
|
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i915.avail_planes_per_pipe
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|
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For example, if we set ``i915.avail_planes_per_pipe=0x030901`` in SOS
|
|
and ``i915.avail_planes_per_pipe=0x04060E`` in UOS, the planes will be as
|
|
shown in :numref:`i915-avail-planes-example1` and
|
|
:numref:`i915-avail-planes-example1`:
|
|
|
|
.. figure:: images/i915-image4.png
|
|
:width: 500px
|
|
:align: center
|
|
:name: i915-avail-planes-example1
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|
|
|
SOS i915.avail_planes_per_pipe
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|
|
|
.. figure:: images/i915-image5.png
|
|
:width: 500px
|
|
:align: center
|
|
:name: i915-avail-planes-example2
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|
|
UOS i915.avail_planes_per_pipe
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|
|
|
``i915.avail_planes_per_pipe`` controls the view of planes from i915 drivers
|
|
inside of every domain, and ``i915.domain_plane_owners`` is the global
|
|
arbiter controlling which domain can present its content onto the
|
|
real hardware. Generally, they are aligned. For example, we can set
|
|
``i915.domain_plane_owners= 0x011111110000``,
|
|
``i915.avail_planes_per_pipe=0x00000F`` in SOS, and
|
|
``i915.avail_planes_per_pipe=0x070F00`` in domain 1, so every domain will
|
|
only flip on the planes they owns.
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|
|
|
However, we don't force alignment: ``avail_planes_per_pipe`` might
|
|
not be aligned with the
|
|
setting of ``domain_plane_owners``. Consider this example:
|
|
``i915.domain_plane_owners=0x011111110000``,
|
|
``i915.avail_planes_per_pipe=0x01010F`` in SOS and
|
|
``i915.avail_planes_per_pipe=0x070F00`` in domain 1.
|
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With this configuration, SOS will be able to render on plane 1B and
|
|
plane 1C, however, the content of plane 1B and plane 1C will not be
|
|
flipped onto the real hardware.
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|
|
|
i915.domain_scaler_owner
|
|
========================
|
|
|
|
On each Intel GPU display pipeline, there are several plane scalers
|
|
to zoom in/out the planes. For example, if a 720p video is played
|
|
full-screen on a 1080p display monitor, the kernel driver will use a
|
|
scaler to zoom in the video plane to a 1080p image and present it onto a
|
|
display pipeline. (Refer to "Intel Open Source Graphics PRM Vol 7:
|
|
display" for the details.)
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|
|
|
On Broxton platforms, Pipe A and Pipe B each
|
|
have two plane scalers, and Pipe C has one plane scaler. To support the
|
|
plane scaling in AcrnGT guest OS, we introduced the parameter
|
|
``i915.domain_scaler_owner``, to assign a specific scaler to the target
|
|
guest OS.
|
|
|
|
As with the parameter ``i915.domain_plane_owners``, each nibble of
|
|
``i915.domain_scaler_owner`` represents the domain id that owns the scaler;
|
|
every nibble (4 bits) represents a scaler and every group of 2 nibbles
|
|
represents a pipe. This is a Service OS only configuration and cannot be
|
|
modified at runtime. Domain ID 0x0 is for the Service OS, the User OS
|
|
use domain IDs from 0x1 to 0xF.
|
|
|
|
For example, if we set ``i915.domain_scaler_owner=0x021100``, the SOS
|
|
owns scaler 1A, 2A; UOS #1 owns scaler 1B, 2B; and UOS #2 owns scaler
|
|
1C.
|
|
|
|
i915.enable_hangcheck
|
|
=====================
|
|
|
|
This parameter enable detection of a GPU hang. When enabled, the i915
|
|
will start a timer to check if the workload is completed in a specific
|
|
time. If not, i915 will treat it as a GPU hang and trigger a GPU reset.
|
|
|
|
In AcrnGT, the workload in SOS and UOS can be set to different
|
|
priorities. If SOS is assigned a higher priority than the UOS, the UOS's
|
|
workload might not be able to run on the HW on time. This may lead to
|
|
the guest i915 triggering a hangcheck and lead to a guest GPU reset.
|
|
This reset is unnecessary so we use ``i915.enable_hangcheck=0`` to
|
|
disable this timeout check and prevent guest from triggering unnecessary
|
|
GPU resets.
|