mirror of https://gitee.com/openkylin/qemu.git
32 lines
1.4 KiB
Plaintext
32 lines
1.4 KiB
Plaintext
pci-test is a device used for testing low level IO
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device implements up to three BARs: BAR0, BAR1 and BAR2.
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Each of BAR 0+1 can be memory or IO. Guests must detect
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BAR types and act accordingly.
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BAR 0+1 size is up to 4K bytes each.
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BAR 0+1 starts with the following header:
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typedef struct PCITestDevHdr {
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uint8_t test; <- write-only, starts a given test number
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uint8_t width_type; <- read-only, type and width of access for a given test.
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1,2,4 for byte,word or long write.
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any other value if test not supported on this BAR
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uint8_t pad0[2];
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uint32_t offset; <- read-only, offset in this BAR for a given test
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uint32_t data; <- read-only, data to use for a given test
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uint32_t count; <- for debugging. number of writes detected.
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uint8_t name[]; <- for debugging. 0-terminated ASCII string.
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} PCITestDevHdr;
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All registers are little endian.
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device is expected to always implement tests 0 to N on each BAR, and to add new
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tests with higher numbers. In this way a guest can scan test numbers until it
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detects an access type that it does not support on this BAR, then stop.
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BAR2 is a 64bit memory bar, without backing storage. It is disabled
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by default and can be enabled using the membar=<size> property. This
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can be used to test whether guests handle pci bars of a specific
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(possibly quite large) size correctly.
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