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authorStefan Hajnoczi <stefanha@linux.vnet.ibm.com>2012-08-21 14:40:49 +0100
committerAnthony Liguori <aliguori@us.ibm.com>2012-08-22 10:47:14 -0500
commitea776abca628d855e03c4929da3864985afd8aae (patch)
tree4fd4e37ef15156e195d9f935f865b73f0712d4ea /hw/spapr_pci.c
parent15d9e3bc6af8a56af8c61911aab8453a54795db1 (diff)
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virtio-blk: hide VIRTIO_BLK_F_CONFIG_WCE from old machine types
QEMU has a policy of keeping a stable guest device ABI. When new guest device features are introduced they must not change hardware info seen by existing guests. This is important because operating systems or applications may "fingerprint" the hardware and refuse to run when the hardware changes. To always get the latest guest device ABI, run with x86 machine type "pc". This patch hides the new VIRTIO_BLK_F_CONFIG_WCE virtio feature bit from existing machine types. Only pc-1.2 and later will expose this feature by default. For more info on the VIRTIO_BLK_F_CONFIG_WCE feature bit, see: commit 13e3dce068773c971ff2f19d986378c55897c4a3 Author: Paolo Bonzini <pbonzini@redhat.com> Date: Thu Aug 9 16:07:19 2012 +0200 virtio-blk: support VIRTIO_BLK_F_CONFIG_WCE Also rename VIRTIO_BLK_F_WCACHE to VIRTIO_BLK_F_WCE for consistency with the spec. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Anthony Liguori <aliguori@us.ibm.com> reported: This broke qemu-test because it changed the pc-1.0 machine type: Setting guest RANDOM seed to 47167 *** Running tests *** Running test /tests/finger-print.sh... OK --- fingerprints/pc-1.0.x86_64 2011-12-18 13:08:40.000000000 -0600 +++ fingerprint.txt 2012-08-12 13:30:48.000000000 -0500 @@ -55,7 +55,7 @@ /sys/bus/pci/devices/0000:00:06.0/subsystem_device=0x0002 /sys/bus/pci/devices/0000:00:06.0/class=0x010000 /sys/bus/pci/devices/0000:00:06.0/revision=0x00 -/sys/bus/pci/devices/0000:00:06.0/virtio/host-features=0x710006d4 +/sys/bus/pci/devices/0000:00:06.0/virtio/host-features=0x71000ed4 /sys/class/dmi/id/bios_vendor=Bochs /sys/class/dmi/id/bios_date=01/01/2007 /sys/class/dmi/id/bios_version=Bochs Guest fingerprint changed for pc-1.0! Reported-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'hw/spapr_pci.c')
0 files changed, 0 insertions, 0 deletions