diff options
| author | Eric Farman <farman@linux.vnet.ibm.com> | 2017-05-10 17:53:57 +0200 |
|---|---|---|
| committer | Cornelia Huck <cornelia.huck@de.ibm.com> | 2017-05-19 12:29:01 +0200 |
| commit | fe921fc8b7e92020bb140079a9f47f14fb8e9075 (patch) | |
| tree | b40bd42284828ff0b2908e692369d2f0e84ce29c /pc-bios/s390-ccw/virtio.h | |
| parent | 8edfe85bef669d676ad17cd84b4e3dce43b110e4 (diff) | |
pc-bios/s390-ccw: Get Block Limits VPD device data
The "Block Limits" Inquiry VPD page is optional for any SCSI device,
but if it's supported it provides a hint of the maximum I/O transfer
length for this particular device. If this page is supported by the
disk, let's issue that Inquiry and use the minimum of it and the
SCSI controller limit. That will cover this scenario:
qemu-system-s390x ...
-device virtio-scsi-ccw,id=scsi0,max_sectors=32768 ...
-drive file=/dev/sda,if=none,id=drive0,format=raw ...
-device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,
drive=drive0,id=disk0,max_io_size=1048576
controller: 32768 sectors x 512 bytes/sector = 16777216 bytes
disk: 1048576 bytes
Now that we have a limit for a virtio-scsi disk, compare that with the
limit for the virtio-scsi controller when we actually build the I/O.
The minimum of these two limits should be the one we use.
Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
Message-Id: <20170510155359.32727-7-farman@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Diffstat (limited to 'pc-bios/s390-ccw/virtio.h')
| -rw-r--r-- | pc-bios/s390-ccw/virtio.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/pc-bios/s390-ccw/virtio.h b/pc-bios/s390-ccw/virtio.h index 3388a423e5..1eaf865b1f 100644 --- a/pc-bios/s390-ccw/virtio.h +++ b/pc-bios/s390-ccw/virtio.h @@ -277,6 +277,7 @@ struct VDev { bool scsi_device_selected; ScsiDevice selected_scsi_device; uint64_t netboot_start_addr; + uint32_t max_transfer; }; typedef struct VDev VDev; |