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Date: Wed, 22 Aug 2012 16:13:44 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/2 v1] blkdrv: Add queue limits parameters
 for sg block drive
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To: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, zwanp@cn.ibm.com, linuxram@us.ibm.com, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Cong Meng <mc@linux.vnet.ibm.com>

Il 22/08/2012 15:13, Stefan Hajnoczi ha scritto:
> http://lists.gnu.org/archive/html/qemu-devel/2010-12/msg01741.html
> 
> "This is a real problem in practice. IE. the USB CD-ROM on this POWER7
> blade limits transfers to 0x1e000 bytes for example and the Linux "sr"
> driver on the guest is going to try to give me bigger requests than that
> if I don't start limiting them, which will cause all sort of errors."
> 
> It cannot be fixed for emulated SCSI HBAs in general but it can for
> virtio-scsi.

For disks, this should be fixed simply by using scsi-block instead of
scsi-generic.

CD-ROMs are indeed more complicated because burning CDs cannot be done
with syscalls. :/

Paolo