Re: [PATCH REBASE 5/7] qemu: Introduce QEMU_CAPS_MACHINE_MEMORY_BACKEND

Ján Tomko <jtomko@xxxxxxxxxx> · Tue, 8 Sep 2020 13:21:39 +0200

On a Tuesday in 2020, Michal Privoznik wrote:
This capability corresponds to '-machine memory-backend=' command
line argument. Unfortunately, it is not possible for us to detect
the capability via QMP and therefore we have to have a version
check.

The QEMU capability was introduced in v5.1.0-3-gc556600598.


Please rephrase this or drop the period at the end, e.g.:

QEMU commit v5.1.0-3-gc556600598 introduced the capability.

(to make it easier to select)

Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
---
src/qemu/qemu_capabilities.c                     | 7 +++++++
src/qemu/qemu_capabilities.h                     | 3 +++
tests/qemucapabilitiesdata/caps_5.2.0.x86_64.xml | 1 +
3 files changed, 11 insertions(+)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index dcfd7cdd4e..d0a7c7b30e 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -597,6 +597,9 @@ VIR_ENUM_IMPL(virQEMUCaps,
              "spapr-tpm-proxy",
              "numa.hmat",
              "blockdev-hostdev-scsi",
+
+              /* 380 */
+              "machine.memory-backend",
    );


@@ -5104,6 +5107,10 @@ virQEMUCapsInitQMPVersionCaps(virQEMUCapsPtr qemuCaps)
    /* TCG couldn't be disabled nor queried until QEMU 2.10 */
    if (qemuCaps->version < 2010000)
        virQEMUCapsSet(qemuCaps, QEMU_CAPS_TCG);
+
+    /* no way to query for -machine memory-backend */
+    if (qemuCaps->version >= 5001050)

That's a git version.

Also, the above mentioned commit introduces the 'default-ram-id'
property, which does show up in our capability replies file.

Can't we safely assume that its presence also means that -machine
memory-backend is supported?

Jano

+        virQEMUCapsSet(qemuCaps, QEMU_CAPS_MACHINE_MEMORY_BACKEND);
}


diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
index 5d08941538..9b2842e84b 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -578,6 +578,9 @@ typedef enum { /* virQEMUCapsFlags grouping marker for syntax-check */
    QEMU_CAPS_NUMA_HMAT, /* -numa hmat */
    QEMU_CAPS_BLOCKDEV_HOSTDEV_SCSI, /* -blockdev used for (i)SCSI hostdevs */

+    /* 380 */
+    QEMU_CAPS_MACHINE_MEMORY_BACKEND, /* -machine memory-backend */
+
    QEMU_CAPS_LAST /* this must always be the last item */
} virQEMUCapsFlags;

diff --git a/tests/qemucapabilitiesdata/caps_5.2.0.x86_64.xml b/tests/qemucapabilitiesdata/caps_5.2.0.x86_64.xml
index 151bd18137..11eb15ca6a 100644
--- a/tests/qemucapabilitiesdata/caps_5.2.0.x86_64.xml
+++ b/tests/qemucapabilitiesdata/caps_5.2.0.x86_64.xml
@@ -242,6 +242,7 @@
  <flag name='intel-iommu.aw-bits'/>
  <flag name='numa.hmat'/>
  <flag name='blockdev-hostdev-scsi'/>
+  <flag name='machine.memory-backend'/>
  <version>5001050</version>
  <kvmVersion>0</kvmVersion>
  <microcodeVersion>43100243</microcodeVersion>
--
2.26.2

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