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From: Tom Yan <1893634@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1893634] [NEW] blk_get_max_transfer() works only with sg
Date: Mon, 31 Aug 2020 10:24:49 -0000	[thread overview]
Message-ID: <159886949002.28151.4021199873744523881.malonedeb@soybean.canonical.com> (raw)

Public bug reported:

blk_get_max_transfer() is supposed to be able to get the max_sectors
queue limit of the scsi device on the host side and is used in both
scsi-generic.c (for scsi-generic and scsi-block) and scsi-disk.c (for
scsi-hd) to set/change the max_xfer_len (and opt_xfer_len in the case of
scsi-generic).

However, it only works with the sg driver in doing so. It cannot get the
queue limit with the sd driver and simply returns MAX_INT.

qemu version 5.1.0
kernel version 5.8.5

Btw, is there a particular reason that it doesn't MIN_NON_ZERO against
the original max_xfer_len:
https://github.com/qemu/qemu/blob/v5.1.0/hw/scsi/scsi-generic.c#L172?

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1893634

Title:
  blk_get_max_transfer() works only with sg

Status in QEMU:
  New

Bug description:
  blk_get_max_transfer() is supposed to be able to get the max_sectors
  queue limit of the scsi device on the host side and is used in both
  scsi-generic.c (for scsi-generic and scsi-block) and scsi-disk.c (for
  scsi-hd) to set/change the max_xfer_len (and opt_xfer_len in the case
  of scsi-generic).

  However, it only works with the sg driver in doing so. It cannot get
  the queue limit with the sd driver and simply returns MAX_INT.

  qemu version 5.1.0
  kernel version 5.8.5

  Btw, is there a particular reason that it doesn't MIN_NON_ZERO against
  the original max_xfer_len:
  https://github.com/qemu/qemu/blob/v5.1.0/hw/scsi/scsi-generic.c#L172?

To manage notifications about this bug go to:
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             reply	other threads:[~2020-08-31 10:31 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-31 10:24 Tom Yan [this message]
2020-08-31 11:08 ` [Bug 1893634] Re: blk_get_max_transfer() works only with sg Tom Yan
2021-05-08  6:11 ` Thomas Huth
2021-07-08  4:17 ` Launchpad Bug Tracker

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