Add a new '[,dump_guest_core=on|off]' option to the '-machine' option. When
'dump_guest_core=off' is specified, guest memory is omitted from the core dump.
The default behavior continues to be to include guest memory when a core dump is
triggered. In my testing, this brought the core dump size down from 384MB to 6MB
on a 2GB guest.
Changelog:
v2: move the option from -m to -machine, rename option dump -> dump_guest_core
Signed-off-by: Jason Baron <jba...@redhat.com>
---
exec.c | 13 +++++++++++++
osdep.h | 7 +++++++
qemu-config.c | 4 ++++
qemu-options.hx | 5 ++++-
sysemu.h | 1 +
vl.c | 4 ++++
6 files changed, 33 insertions(+), 1 deletions(-)
diff --git a/exec.c b/exec.c
index feb4795..0764818 100644
--- a/exec.c
+++ b/exec.c
@@ -35,6 +35,7 @@
#include "qemu-timer.h"
#include "memory.h"
#include "exec-memory.h"
+#include "sysemu.h"
#if defined(CONFIG_USER_ONLY)
#include <qemu.h>
#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
@@ -2514,6 +2515,7 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void
*host,
MemoryRegion *mr)
{
RAMBlock *new_block;
+ int ret;
size = TARGET_PAGE_ALIGN(size);
new_block = g_malloc0(sizeof(*new_block));
@@ -2555,6 +2557,17 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void
*host,
last_ram_offset() >> TARGET_PAGE_BITS);
cpu_physical_memory_set_dirty_range(new_block->offset, size, 0xff);
+
+ /* Use MADV_DONTDUMP, if user doesn't want the guest memory in the core */
+ if (dont_dump_guest_core) {
+ ret = qemu_madvise(new_block->host, size, QEMU_MADV_DONTDUMP);
+ if (ret) {
+ perror("qemu_madvise");
+ fprintf(stderr, "madvise doesn't support MADV_DONTDUMP, "
+ "but dump_guest_core=off specified\n");
+ }
+ }
+
if (kvm_enabled())
kvm_setup_guest_memory(new_block->host, size);
diff --git a/osdep.h b/osdep.h
index 1e15a4b..e2d0f57 100644
--- a/osdep.h
+++ b/osdep.h
@@ -102,6 +102,11 @@ void qemu_vfree(void *ptr);
#else
#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
#endif
+#ifdef MADV_DONTDUMP
+#define QEMU_MADV_DONTDUMP MADV_DONTDUMP
+#else
+#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID
+#endif
#elif defined(CONFIG_POSIX_MADVISE)
@@ -109,6 +114,7 @@ void qemu_vfree(void *ptr);
#define QEMU_MADV_DONTNEED POSIX_MADV_DONTNEED
#define QEMU_MADV_DONTFORK QEMU_MADV_INVALID
#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
+#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID
#else /* no-op */
@@ -116,6 +122,7 @@ void qemu_vfree(void *ptr);
#define QEMU_MADV_DONTNEED QEMU_MADV_INVALID
#define QEMU_MADV_DONTFORK QEMU_MADV_INVALID
#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
+#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID
#endif
diff --git a/qemu-config.c b/qemu-config.c
index 5c3296b..5c2c9a9 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -595,6 +595,10 @@ static QemuOptsList qemu_machine_opts = {
.name = "dt_compatible",
.type = QEMU_OPT_STRING,
.help = "Overrides the \"compatible\" property of the dt root
node",
+ }, {
+ .name = "dump_guest_core",
+ .type = QEMU_OPT_BOOL,
+ .help = "Include guest memory in a core dump",
},
{ /* End of list */ }
},
diff --git a/qemu-options.hx b/qemu-options.hx
index dc68e15..e917829 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -33,7 +33,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
" property accel=accel1[:accel2[:...]] selects
accelerator\n"
" supported accelerators are kvm, xen, tcg (default: tcg)\n"
" kernel_irqchip=on|off controls accelerated irqchip
support\n"
- " kvm_shadow_mem=size of KVM shadow MMU\n",
+ " kvm_shadow_mem=size of KVM shadow MMU\n"
+ " dump_guest_core=on|off include guest memory in a core
dump (default=on)\n",
QEMU_ARCH_ALL)
STEXI
@item -machine [type=]@var{name}[,prop=@var{value}[,...]]
@@ -50,6 +51,8 @@ to initialize.
Enables in-kernel irqchip support for the chosen accelerator when available.
@item kvm_shadow_mem=size
Defines the size of the KVM shadow MMU.
+@item dump_guest_core=on|off
+Include guest memory in a core dump. The default is on.
@end table
ETEXI
diff --git a/sysemu.h b/sysemu.h
index 6540c79..caf33ce 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -132,6 +132,7 @@ extern uint8_t *boot_splash_filedata;
extern int boot_splash_filedata_size;
extern uint8_t qemu_extra_params_fw[2];
extern QEMUClock *rtc_clock;
+extern int dont_dump_guest_core;
#define MAX_NODES 64
extern int nb_numa_nodes;
diff --git a/vl.c b/vl.c
index c18bb80..accfd28 100644
--- a/vl.c
+++ b/vl.c
@@ -226,6 +226,7 @@ int boot_menu;
uint8_t *boot_splash_filedata;
int boot_splash_filedata_size;
uint8_t qemu_extra_params_fw[2];
+int dont_dump_guest_core;
typedef struct FWBootEntry FWBootEntry;
@@ -2976,6 +2977,9 @@ int main(int argc, char **argv, char **envp)
if (optarg) {
machine = machine_parse(optarg);
}
+ if (!qemu_opt_get_bool(opts, "dump_guest_core", true)) {
+ dont_dump_guest_core = 1;
+ }
break;
case QEMU_OPTION_usb:
usb_enabled = 1;
--
1.7.1
