On 1/10/19 7:15 AM, Nikolay Shirokovskiy wrote:
For qemu capable of setting l2-cache-size for qcow2 images to INT64_MAX and semantics of upper limit on l2 cache size. We can only check this by qemu version (3.1.0) now.
Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@virtuozzo.com> --- src/qemu/qemu_capabilities.c | 5 +++++ src/qemu/qemu_capabilities.h | 1 + 2 files changed, 6 insertions(+)
I posted a patch series today that would add/update the capabilities for 3.1 (and 4.0) and thus would add this capability to this patch. However, given that the only way you've chosen to support/implement this is via -blockdev, I'm not sure now what the purpose will be unless it's used to determine whether to use INT64_MAX or some other value. I see from previous series that it seems to be possible to have: -drive xxx,format=qcow2,l2-cache-size=VALUE,... However, patch3 notes in the commit message that "-drive configuration is not supported because we can not set l2 cache size down the backing chain in this case." So if -blockdev is going to be your the option for support, then I think it'd be wiser to wait for Peter to finish -blockdev support before acting on this. Since -blockdev support allows some qemu version earlier the 3.1 to be supported, then we revisit this. Additionally, referencing Leonid's qemu.git commit b749562d98 as the "arbiter" of why INT64_MAX must be used (since calculating a max max value isn't possible, IIRC). John
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index f504db7..e09b13a 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -520,6 +520,7 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST, /* 325 */ "memory-backend-file.pmem", "nvdimm.unarmed", + "qcow2.l2-cache-size.capped", );
@@ -4256,6 +4257,10 @@ virQEMUCapsInitQMPMonitor(virQEMUCapsPtr qemuCaps, virQEMUCapsSet(qemuCaps, QEMU_CAPS_MACHINE_PSERIES_MAX_CPU_COMPAT); }
+ /* l2-cache-size before 3001000 does not accept INT64_MAX */ + if (qemuCaps->version >= 3001000) + virQEMUCapsSet(qemuCaps, QEMU_CAPS_QCOW2_L2_CACHE_SIZE_CAPPED); + if (virQEMUCapsProbeQMPCommands(qemuCaps, mon) < 0) goto cleanup;
diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h index 6d5ed8a..e17a1dc 100644 --- a/src/qemu/qemu_capabilities.h +++ b/src/qemu/qemu_capabilities.h @@ -504,6 +504,7 @@ typedef enum { /* virQEMUCapsFlags grouping marker for syntax-check */ /* 325 */ QEMU_CAPS_OBJECT_MEMORY_FILE_PMEM, /* -object memory-backend-file,pmem= */ QEMU_CAPS_DEVICE_NVDIMM_UNARMED, /* -device nvdimm,unarmed= */ + QEMU_CAPS_QCOW2_L2_CACHE_SIZE_CAPPED, /* -blockdev supports l2-cache-size with INT64_MAX value */
QEMU_CAPS_LAST /* this must always be the last item */ } virQEMUCapsFlags;