Add a new '[,dump=on|off]' option to the '-m' memory option. When 'dump=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 6 MB on a 2GB guest.
Thanks to Avi Kivity for the command line syntax.
Signed-off-by: Jason Baron <jba...@redhat.com>
---
exec.c | 13 +++++++++++++
osdep.h | 7 +++++++
qemu-options.hx | 11 +++++++----
sysemu.h | 1 +
vl.c | 51 +++++++++++++++++++++++++++++++++++----------------
5 files changed, 63 insertions(+), 20 deletions(-)
diff --git a/exec.c b/exec.c
index feb4795..75b8e23 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) {
+ 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=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-options.hx b/qemu-options.hx
index dc68e15..9c21b99 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -382,14 +382,17 @@ the write back by pressing @key{C-a s}
(@pxref{disk_images}).
ETEXI
DEF("m", HAS_ARG, QEMU_OPTION_m,
- "-m megs set virtual RAM size to megs MB [default="
- stringify(DEFAULT_RAM_SIZE) "]\n", QEMU_ARCH_ALL)
+ "-m megs[,dump=on|off]\n"
+ " set virtual RAM size to megs MB [default="
stringify(DEFAULT_RAM_SIZE) "]\n"
+ " use 'dump=off' to omit guest memory from a core dump
[default=on]\n",
+ QEMU_ARCH_ALL)
STEXI
-@item -m @var{megs}
+@item -m @var{megs}[,dump=on|off]
@findex -m
Set virtual RAM size to @var{megs} megabytes. Default is 128 MiB. Optionally,
a suffix of ``M'' or ``G'' can be used to signify a value in megabytes or
-gigabytes respectively.
+gigabytes respectively. When 'dump=off' is specified, the guest memory is
omitted
+from a qemu core dump. The default is 'dump=on'.
ETEXI
DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
diff --git a/sysemu.h b/sysemu.h
index 6540c79..f1a6f08 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;
#define MAX_NODES 64
extern int nb_numa_nodes;
diff --git a/vl.c b/vl.c
index c18bb80..54ff314 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;
typedef struct FWBootEntry FWBootEntry;
@@ -1041,6 +1042,38 @@ static void smp_parse(const char *optarg)
max_cpus = smp_cpus;
}
+static void memory_parse(const char *optarg)
+{
+ char option[128];
+ int64_t value;
+ char *end;
+
+ optarg = get_opt_name(option, 128, optarg, ',');
+ value = strtosz(option, &end);
+ if (value < 0 || (*end && (*end != ','))) {
+ fprintf(stderr, "qemu: invalid ram size: %s\n", option);
+ exit(1);
+ }
+ if (value != (uint64_t)(ram_addr_t)value) {
+ fprintf(stderr, "qemu: ram size too large\n");
+ exit(1);
+ }
+ ram_size = value;
+ if (*optarg == ',') {
+ optarg++;
+ }
+ if (get_param_value(option, 128, "dump", optarg) != 0) {
+ if (!strcmp(option, "on")) {
+ dont_dump_guest = 0;
+ } else if (!strcmp(option, "off")) {
+ dont_dump_guest = 1;
+ } else {
+ fprintf(stderr, "qemu: invalid option value '%s'\n", option);
+ exit(1);
+ }
+ }
+}
+
/***********************************************************/
/* USB devices */
@@ -2650,23 +2683,9 @@ int main(int argc, char **argv, char **envp)
version();
exit(0);
break;
- case QEMU_OPTION_m: {
- int64_t value;
- char *end;
-
- value = strtosz(optarg, &end);
- if (value < 0 || *end) {
- fprintf(stderr, "qemu: invalid ram size: %s\n", optarg);
- exit(1);
- }
-
- if (value != (uint64_t)(ram_addr_t)value) {
- fprintf(stderr, "qemu: ram size too large\n");
- exit(1);
- }
- ram_size = value;
+ case QEMU_OPTION_m:
+ memory_parse(optarg);
break;
- }
case QEMU_OPTION_mempath:
mem_path = optarg;
break;
--
1.7.1
