2:04 a.m.
*** BLURB HERE ***
Michal Prívozník (2):
qemu.conf.in: Fix dumpCore capitalization
qemu: Provide sane default for dump_guest_core
meson.build | 1 +
src/qemu/qemu.conf.in | 4 ++--
src/qemu/qemu_conf.c | 11 +++++++++++
tests/testutilsqemu.c | 2 ++
4 files changed, 16 insertions(+), 2 deletions(-)
--
2.44.2
2:04 a.m.
New subject: [PATCH 1/2] qemu.conf.in: Fix dumpCore capitalization
In qemu.conf.in we give examples of enabling/disabling core
dumps in domain XML. But the attribute is spelled wrong.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/qemu/qemu.conf.in | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/qemu/qemu.conf.in b/src/qemu/qemu.conf.in
index 6bc2140dcb..e1f3046177 100644
--- a/src/qemu/qemu.conf.in
+++ b/src/qemu/qemu.conf.in
@@ -692,7 +692,7 @@
# guest RAM, if the 'dump_guest_core' setting has been enabled,
# or if the guest XML contains
#
-# <memory dumpcore="on">...guest ram...</memory>
+# <memory dumpCore="on">...guest ram...</memory>
#
# If guest RAM is to be included, ensure the max_core limit
# is set to at least the size of the largest expected guest
@@ -714,7 +714,7 @@
# be included in QEMU core dumps.
#
# This setting will be ignored if the guest XML has set the
-# dumpcore attribute on the <memory> element.
+# dumpCore attribute on the <memory> element.
#
#dump_guest_core = 1
--
2.44.2
2:04 a.m.
New subject: [PATCH 2/2] qemu: Provide sane default for dump_guest_core
QEMU uses Linux extensions to madvise() to include/exclue guest
memory from core dump. These are obviously not available
everywhere. Currently, users have two options:
1) configure <memory dumpCore=''/> in domain XML, or
2) configure dump_guest_core in qemu.conf
While these work, they may harm user experience as "things just
don't work" out of the box. Provide sane default in
virQEMUDriverConfigNew() so neither of two options is required.
To have predictable results in tests, explicitly set
cfg->dumpGuestCore to false in qemuTestDriverInit() (which
creates cfg object for tests).
Resolves: https://gitlab.com/libvirt/libvirt/-/issues/679
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
meson.build | 1 +
src/qemu/qemu_conf.c | 11 +++++++++++
tests/testutilsqemu.c | 2 ++
3 files changed, 14 insertions(+)
diff --git a/meson.build b/meson.build
index 4c6e5a088e..aa6b8ce5aa 100644
--- a/meson.build
+++ b/meson.build
@@ -676,6 +676,7 @@ headers = [
'sched.h',
'sys/auxv.h',
'sys/ioctl.h',
+ 'sys/mman.h',
'sys/mount.h',
'sys/syscall.h',
'sys/ucred.h',
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index b36bede6c3..2c4e6a74cb 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -26,6 +26,10 @@
#include <unistd.h>
#include <fcntl.h>
+#ifdef WITH_SYS_MMAN_H
+# include <sys/mman.h>
+#endif
+
#include "virerror.h"
#include "qemu_conf.h"
#include "qemu_capabilities.h"
@@ -287,6 +291,13 @@ virQEMUDriverConfig *virQEMUDriverConfigNew(bool privileged,
cfg->deprecationBehavior = g_strdup("none");
cfg->storageUseNbdkit = USE_NBDKIT_DEFAULT;
+#ifndef MADV_DONTDUMP
+ /* QEMU uses Linux extensions to madvise() (MADV_DODUMP/MADV_DONTDUMP) to
+ * include/exclude guest memory from core dump. These might be unavailable
+ * on some systems. Provide sane default. */
+ cfg->dumpGuestCore = true;
+#endif
+
return g_steal_pointer(&cfg);
}
diff --git a/tests/testutilsqemu.c b/tests/testutilsqemu.c
index ee6cae218a..4daee432e5 100644
--- a/tests/testutilsqemu.c
+++ b/tests/testutilsqemu.c
@@ -407,6 +407,8 @@ int qemuTestDriverInit(virQEMUDriver *driver)
cfg->hugetlbfs[0].deflt = true;
cfg->hugetlbfs[1].size = 1048576;
+ cfg->dumpGuestCore = false;
+
driver->privileged = true;
return 0;
--
2.44.2
2:51 a.m.
New subject: [PATCH 2/2] qemu: Provide sane default for dump_guest_core
On Thu, Sep 19, 2024 at 09:04:11AM +0200, Michal Privoznik wrote:
QEMU uses Linux extensions to madvise() to include/exclue guest
s/exclue/exclude/
memory from core dump. These are obviously not available
everywhere. Currently, users have two options:
1) configure <memory dumpCore=''/> in domain XML, or
2) configure dump_guest_core in qemu.conf
While these work, they may harm user experience as "things just
don't work" out of the box. Provide sane default in
virQEMUDriverConfigNew() so neither of two options is required.
To have predictable results in tests, explicitly set
cfg->dumpGuestCore to false in qemuTestDriverInit() (which
creates cfg object for tests).
Resolves: https://gitlab.com/libvirt/libvirt/-/issues/679
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
meson.build | 1 +
src/qemu/qemu_conf.c | 11 +++++++++++
tests/testutilsqemu.c | 2 ++
3 files changed, 14 insertions(+)
diff --git a/meson.build b/meson.build
index 4c6e5a088e..aa6b8ce5aa 100644
--- a/meson.build
+++ b/meson.build
@@ -676,6 +676,7 @@ headers = [
'sched.h',
'sys/auxv.h',
'sys/ioctl.h',
+ 'sys/mman.h',
'sys/mount.h',
'sys/syscall.h',
'sys/ucred.h',
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index b36bede6c3..2c4e6a74cb 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -26,6 +26,10 @@
#include <unistd.h>
#include <fcntl.h>
+#ifdef WITH_SYS_MMAN_H
+# include <sys/mman.h>
+#endif
+
#include "virerror.h"
#include "qemu_conf.h"
#include "qemu_capabilities.h"
@@ -287,6 +291,13 @@ virQEMUDriverConfig *virQEMUDriverConfigNew(bool privileged,
cfg->deprecationBehavior = g_strdup("none");
cfg->storageUseNbdkit = USE_NBDKIT_DEFAULT;
+#ifndef MADV_DONTDUMP
+ /* QEMU uses Linux extensions to madvise() (MADV_DODUMP/MADV_DONTDUMP) to
+ * include/exclude guest memory from core dump. These might be unavailable
+ * on some systems. Provide sane default. */
+ cfg->dumpGuestCore = true;
+#endif
+
I'd like a VIR_INFO or something here to see that we're not able to
exclude that from the dump, just in case someone is trying to figure
that out from the logs.
Also the qemu.conf file says it *will* be disabled by default, so maybe
adjusting the wording with something like "if possible" added there
might be worth it. Simply to avoid further issues being filed.
return g_steal_pointer(&cfg);
}
diff --git a/tests/testutilsqemu.c b/tests/testutilsqemu.c
index ee6cae218a..4daee432e5 100644
--- a/tests/testutilsqemu.c
+++ b/tests/testutilsqemu.c
@@ -407,6 +407,8 @@ int qemuTestDriverInit(virQEMUDriver *driver)
cfg->hugetlbfs[0].deflt = true;
cfg->hugetlbfs[1].size = 1048576;
+ cfg->dumpGuestCore = false;
+
driver->privileged = true;
return 0;
--
2.44.2
94
days inactive
94
days old
3 comments
2 participants
participants (2)
-
Martin Kletzander -
Michal Privoznik