Re: [Qemu-devel] [PATCH v2 3/3] ahci-test: test atapi read_cd with bcl, nb_sectors = 0

[Kevin Wolf <kwolf@redhat.com>]

Am 02.11.2016 um 16:01 hat John Snow geschrieben:
> 
> 
> On 11/02/2016 09:33 AM, Kevin Wolf wrote:
> >Am 01.11.2016 um 04:16 hat John Snow geschrieben:
> >>Commit 9ef2e93f introduced the concept of tagging ATAPI commands as
> >>NONDATA, but this introduced a regression for certain commands better
> >>described as CONDDATA. read_cd is such a command that both requires
> >>a non-zero BCL if a transfer size is set, but is perfectly content to
> >>accept a zero BCL if the transfer size is 0.
> >>
> >>This test adds a regression test for the case where BCL and nb_sectors
> >>are both 0.
> >>
> >>Flesh out the CDROM tests by:
> >>
> >>(1) Allowing the test to specify a BCL
> >>(2) Allowing the buffer comparison test to compare a 0-size buffer
> >>(3) Fix the BCL specification in libqos (It is LE, not BE)
> >>(4) Add a nice human-readable message for future SCSI command additions
> >>
> >>Signed-off-by: John Snow <jsnow@redhat.com>
> >
> >>diff --git a/tests/libqos/ahci.c b/tests/libqos/ahci.c
> >>index 5180d65..15fa888 100644
> >>--- a/tests/libqos/ahci.c
> >>+++ b/tests/libqos/ahci.c
> >>@@ -864,16 +865,12 @@ AHCICommand *ahci_command_create(uint8_t command_name)
> >>     return cmd;
> >> }
> >>
> >>-AHCICommand *ahci_atapi_command_create(uint8_t scsi_cmd)
> >>+AHCICommand *ahci_atapi_command_create(uint8_t scsi_cmd, uint16_t bcl)
> >> {
> >>     AHCICommand *cmd = ahci_command_create(CMD_PACKET);
> >>     cmd->atapi_cmd = g_malloc0(16);
> >>     cmd->atapi_cmd[0] = scsi_cmd;
> >>-    /* ATAPI needs a PIO transfer chunk size set inside of the LBA registers.
> >>-     * The block/sector size is a natural default. */
> >>-    cmd->fis.lba_lo[1] = ATAPI_SECTOR_SIZE >> 8 & 0xFF;
> >>-    cmd->fis.lba_lo[2] = ATAPI_SECTOR_SIZE & 0xFF;
> >>-
> >>+    stw_le_p(&cmd->fis.lba_lo[1], bcl);
> >>     return cmd;
> >> }
> >
> >If I'm not mistaken, you're changing the endianness here, which seems
> >to be a silent bug fix.
> >
> >For some reason the test passes both ways. Does the actual value even
> >matter with AHCI, as long as it's non-zero? Do we end up with the same
> >result with BCL=0x0200 and BCL=0x0002, just that we split it into some
> >more iterations for the latter (or deeper recursion, actually)?
> >
> >Kevin
> >
> 
> Well, not silent, I did mention it in the cover letter. Your
> analysis of the mistake is correct. One way is just simply more
> iterations.

You mean I'm supposed to actually read commit messages...?

Sorry for the noise, looks good then.

Kevin