On Tue, Sep 07, 2021 at 15:12:09 +0800, yuxiating@huawei.com wrote:
From: yuxiating <yuxiating@huawei.com>
DISCARD and WRITE_ZEROES features for machine type >= 4.0 is enabled by default since 5c81161f8041("virtio-blk: add "discard" and "write-zeroes" properties). Virtio_blk kernel driver has a bug that causes memory corruption in virtblk_setup_discard_write_zeroes(); af822aa68fbd ("block: virtio_blk: fix handling single range discard request") has fix it. However, some operating systems are not fixed and need to disabled on the QEMU side.
I must say that I'm not persuaded that there's enough value in this workaround. Similarly users could use virtio-scsi instead as a workaround or fix their OS. For me this reasoning will not be enough, but other on the list might think otherwise.
Signed-off-by: yuxiating <yuxiating@huawei.com> --- docs/formatdomain.rst | 3 +++ docs/schemas/domaincommon.rng | 8 ++++++++ src/conf/domain_conf.c | 8 ++++++++ src/conf/domain_conf.h | 1 + src/conf/domain_validate.c | 6 ++++++ 5 files changed, 26 insertions(+)
[...]
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 6127513117..304015f42e 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c
[...]
@@ -23416,6 +23420,10 @@ virDomainDiskDefFormatDriver(virBuffer *buf, if (disk->queues) virBufferAsprintf(&attrBuf, " queues='%u'", disk->queues);
+ if (disk->discard_enable)
We tend to use explicit check: if (disk->discard_enable != VIR_TRISTATE_BOOL_ABSENT)
+ virBufferAsprintf(&attrBuf, " discard_enable='%s'", + virTristateSwitchTypeToString(disk->discard_enable)); + virDomainVirtioOptionsFormat(&attrBuf, disk->virtio);
if (disk->src->metadataCacheMaxSize > 0) {
This definitely seems like a feature visible to the guest OS and thus _must_ be covered by the ABI stability check to prevent regressions in the ABI. See 'virDomainDiskDefCheckABIStability'.