mirror of https://github.com/proxmox/mirror_qemu
ef5bc96268
The following sequence happens: - the SeaBIOS virtio-blk driver does not support the WCE feature, which causes QEMU to disable writeback caching - the Linux virtio-blk driver resets the device, finds WCE is available but writeback caching is disabled; tells block layer to not send cache flush commands - the Linux virtio-blk driver sets the DRIVER_OK bit, which causes writeback caching to be re-enabled, but the Linux virtio-blk driver does not know of this side effect and cache flushes remain disabled The bug is at the third step. If the guest does know about CONFIG_WCE, QEMU should ignore the WCE feature's state. The guest will control the cache mode solely using configuration space. This change makes Linux do flushes correctly, but Linux will keep SeaBIOS's writethrough mode. Hence, whenever the guest is reset, the cache mode of the disk should be reset to whatever was specified in the "-drive" option. With this change, the Linux virtio-blk driver finds that writeback caching is enabled, and tells the block layer to send cache flush commands appropriately. Reported-by: Rusty Russell <rusty@au1.ibm.com Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> |
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| .. | ||
| dataplane | ||
| Makefile.objs | ||
| block.c | ||
| cdrom.c | ||
| ecc.c | ||
| fdc.c | ||
| hd-geometry.c | ||
| m25p80.c | ||
| nand.c | ||
| nvme.c | ||
| nvme.h | ||
| onenand.c | ||
| pflash_cfi01.c | ||
| pflash_cfi02.c | ||
| tc58128.c | ||
| virtio-blk.c | ||
| xen_blkif.h | ||
| xen_disk.c | ||