On 03/27/20 23:17, Liran Alon wrote:
> Furthermore, I have later found ScsiExecuteSCSICommand() in
> MdeModulePkg/Bus/Scsi/ScsiBusDxe/ScsiBus.c to be the one that calls the
> PassThru() method.
> Looking at it's "if (ScsiIoDevice->ExtScsiSupport)" branch (Which is
> relevant to us), one can see it just simply executes the PassThru()
> device and returns.
> Examining ScsiExecuteSCSICommand() documentation specifies for
> EFI_BAD_BUFFER_SIZE:
>
> @retval EFI_BAD_BUFFER_SIZE The SCSI Request Packet was executed,
> but the entire DataBuffer could not be
> transferred.
> The actual number of bytes transferred is
> returned
> in TransferLength. See HostAdapterStatus,
> TargetStatus, SenseDataLength, and
> SenseData in
> that order for additional status information.
>
(1) The commit that added the "ScsiIoDevice->ExtScsiSupport" branch to
ScsiExecuteSCSICommand() was 70c94b3b6ddf ("Porting R8's PI-enabled ScsiBus
driver", 2007-07-02).
$ git show -U100 70c94b3b6ddf
At that time, the ScsiExecuteSCSICommand() function had the following
documentation:
EFI_SUCCESS - The SCSI Request Packet was sent by the host
successfully, and TransferLength bytes were
transferred to/from DataBuffer.See
HostAdapterStatus, TargetStatus,
SenseDataLength, and SenseData in that order
for additional status information.
EFI_WARN_BUFFER_TOO_SMALL - The SCSI Request Packet was executed,
but the entire DataBuffer could not be transferred.
The actual number of bytes transferred is returned
in TransferLength. See HostAdapterStatus,
TargetStatus, SenseDataLength, and SenseData in
that order for additional status information.
No "EFI_BAD_BUFFER_SIZE".
So commit 70c94b3b6ddf was not entirely correct, because after it, the
ScsiExecuteSCSICommand() could return EFI_BAD_BUFFER_SIZE (propagating it from
ScsiIoDevice->ExtScsiPassThru->PassThru()), but the function's documentation
was not updated.
(At the same commit, "MdePkg/Include/Protocol/ScsiPassThruExt.h" already
specified EFI_BAD_BUFFER_SIZE as "The SCSI Request Packet was not executed" --
that had come from commit d1f950002362, "Checked in the Protocols introduced in
UEFI/PI.", 2007-06-19.)
(2) In commit f36d6e669c97 (2007-09-20), the leading comment block on
ScsiExecuteSCSICommand() was updated. The EFI_WARN_BUFFER_TOO_SMALL retval
disappeared, and the incorrect EFI_BAD_BUFFER_SIZE language ("The SCSI Request
Packet was executed") appeared. (Incorrect for the "EXT" passthru, anyway.)
Interestingly, in this commit message, we see:
3. Correctify some return status to sync with newest Uefi Spec 2.1
However, in the UEFI 2.0 spec
<http://www.uefi.org/sites/default/files/resources/UEFI_Specification_2_and_Errata_Sept16_08.pdf>,
EFI_BAD_BUFFER_SIZE is already defined as "The SCSI Request Packet was not
executed".
So I think it's a bug in edk2 (at least a documentation bug).
Thanks
Laszlo
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