Re: [libvirt] [PATCH] qemu: treat iso images as raw

On Thu, Oct 26, 2017 at 13:09:25 +0100, Daniel Berrange wrote: > On Thu, Oct 26, 2017 at 03:04:08PM +0300, Nikolay Shirokovskiy wrote: >> if image format probing is on and image format of iso file >> is not specified qemu fail to start a domain or change disk >> media giving errors like [1]. The problem is format is being >> detected as 'iso' and qemu expect format to be raw for iso >> images. >> >> It makes sense to me because iso refers to filesystem format >> in image not image format itself. Thus let's just convert >> iso to raw in case of qemu. >> >> There is a similar patch for storage pools - 0e5db762. >> >> [1] Unknown driver 'iso' >> >> --- >> >> ISO as image format was added right at the beginning by e266ded2f >> without any further comments. Maybe we just can drop ISO from image >> formats entirely as it is not image format or some hypervisors >> treat it in a special way? > > Yeah, I'm inclined to say we can drop it. I don't recall either Xen or > QEMU caring about an 'iso' disk format The hypervisors probably don't care about this but the storage driver may care (At least for display purposes). >> src/qemu/qemu_domain.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c >> index c7c9e94..3da9271 100644 >> --- a/src/qemu/qemu_domain.c >> +++ b/src/qemu/qemu_domain.c >> @@ -6023,8 +6023,13 @@ qemuDomainDetermineDiskChain(virQEMUDriverPtr driver, >> if (virStorageFileGetMetadata(disk->src, >> uid, gid, >> cfg->allowDiskFormatProbing, >> - report_broken) < 0) >> + report_broken) < 0) { >> ret = -1; >> + goto cleanup; >> + } >> + >> + if (virDomainDiskGetFormat(disk) == VIR_STORAGE_FILE_ISO) >> + virDomainDiskSetFormat(disk, VIR_STORAGE_FILE_RAW); This is not the right place and also not the correct way. We should reject using ISO as a format if qemu will not support it as an invalid configuration rather than silently turn it into raw.

The only acceptable place to turn ISO -> RAW is when it's comming from the storage driver via <disk type=volume>