From: Fam Zheng <famz@redhat.com>
To: Eric Farman <farman@linux.vnet.ibm.com>
Cc: qemu-devel@nongnu.org, "Michael S . Tsirkin" <mst@redhat.com>,
Alexander Graf <agraf@suse.de>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Cornelia Huck <cornelia.huck@de.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [RFC PATCH v1 0/5] Enable virtio-scsi boot from /dev/sgX
Date: Fri, 5 May 2017 15:41:43 +0800 [thread overview]
Message-ID: <20170505074143.GB21435@lemon.lan> (raw)
In-Reply-To: <20170426144645.12476-1-farman@linux.vnet.ibm.com>
On Wed, 04/26 16:46, Eric Farman wrote:
> The short version of what happens is the host device driver rejects our
> requests because the transfer lengths are too long for it to satisfy.
> A virtio-scsi disk connected via scsi-generic is fine as a non-boot device
> because the guest kernel is able to break up the requests for us. So we just
> need to handle this situation for the boot process.
>
> Patches 2-N in this series do that, but rely on us to specify the max_sectors
> parameter for the virtio-scsi-ccw device:
>
> /usr/bin/qemu-system-s390x ...
> -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001,max_sectors=2048
Can you instead do an INQUIRY from the bios code to check the Block Limits page?
The response is intercepted by hw/scsi/scsi-generic.c to merge in the host LUN's
limits. That's how Linux kernel finds the granularity for request splitting.
That way, patch 1 is not necessary too. I don't like it because it doesn't
always work considering LUN hotplug.
Fam
next prev parent reply other threads:[~2017-05-05 7:41 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-26 14:46 [Qemu-devel] [RFC PATCH v1 0/5] Enable virtio-scsi boot from /dev/sgX Eric Farman
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 1/5] hw/scsi: Override the max_sectors value for virtio-scsi Eric Farman
2017-05-05 7:39 ` Paolo Bonzini
2017-05-05 7:50 ` Christian Borntraeger
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 2/5] pc-bios/s390-ccw: Remove duplicate blk_factor adjustment Eric Farman
2017-05-05 7:10 ` Christian Borntraeger
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 3/5] pc-bios/s390-ccw: Move SCSI block factor to outer read Eric Farman
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 4/5] pc-bios/s390-ccw: Break up virtio-scsi read into multiples Eric Farman
2017-04-26 15:17 ` Eric Blake
2017-04-26 15:24 ` Eric Farman
2017-04-26 16:00 ` Eric Farman
2017-04-26 15:47 ` Cornelia Huck
2017-04-26 14:46 ` [Qemu-devel] [RFC PATCH v1 5/5] pc-bios/s390-ccw.img: rebuild image Eric Farman
2017-04-26 15:48 ` [Qemu-devel] [RFC PATCH v1 0/5] Enable virtio-scsi boot from /dev/sgX Christian Borntraeger
2017-04-26 16:13 ` Eric Farman
2017-05-05 7:41 ` Fam Zheng [this message]
2017-05-05 15:03 ` Eric Farman
2017-05-05 15:13 ` Paolo Bonzini
2017-05-05 16:12 ` Eric Farman
2017-05-06 8:24 ` Paolo Bonzini
2017-05-08 7:00 ` Christian Borntraeger
2017-05-08 15:00 ` Eric Farman
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