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45 lines
1.5 KiB
ReStructuredText
45 lines
1.5 KiB
ReStructuredText
.. _ahci-hld:
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AHCI Virtualization in Device Model
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###################################
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AHCI (Advanced Host Controller Interface) is a hardware mechanism
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that allows software to communicate with Serial ATA devices. AHCI HBA
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(host bus adapters) is a PCI class device that acts as a data movement
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engine between system memory and Serial ATA devices. The ACPI HBA in
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ACRN supports both ATA and ATAPI devices. The architecture is shown in
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the below diagram.
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.. figure:: images/ahci-image1.png
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:align: center
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:width: 750px
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:name: achi-device
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HBA is registered to the PCI system with device id 0x2821 and vendor id
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0x8086. Its memory registers are mapped in BAR 5. It only supports 6
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ports (refer to ICH8 AHCI). AHCI driver in the Guest OS can access HBA in DM
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through the PCI BAR. And HBA can inject MSI interrupts through the PCI
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framework.
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When the application in the Guest OS reads data from /dev/sda, the request will
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send through the AHCI driver and then the PCI driver. The Guest VM will trap to
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hypervisor, and hypervisor dispatch the request to DM. According to the
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offset in the BAR, the request will dispatch to port control handler.
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Then the request is parse to a block I/O request which can be processed
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by Block backend model.
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Usage:
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***-s <slot>,ahci,<type:><filepath>***
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Type: ‘hd’ and ‘cd’ are available.
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Filepath: the path for the backend file, could be a partition or a
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regular file.
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E.g．
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SOS: -s 20,ahci,\ `hd:/dev/mmcblk0p1 <http://hd/dev/mmcblk0p1>`__
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UOS: /dev/sda
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