Patchwork [v2] memory: add cmd line option, to omit guest memory from qemu core dump

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Submitter Jason Baron
Date Aug. 1, 2012, 4:19 p.m.
Message ID <201208011619.q71GJSqg017150@int-mx01.intmail.prod.int.phx2.redhat.com>
Download mbox | patch
Permalink /patch/174523/
State New
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Comments

Jason Baron - Aug. 1, 2012, 4:19 p.m.
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 <jbaron@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(-)
Anthony Liguori - Aug. 1, 2012, 6:21 p.m.
Jason Baron <jbaron@redhat.com> writes:

> 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 <jbaron@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) {

    machine_opts = qemu_opts_find(qemu_find_opts("machine"), 0);
    if (machine_opts && qemu_opt_get_bool(machine_opts, "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",

"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;

Drop the globals.

>  
>  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;

The -machine option is not the only way to set machine options so this
is incorrect.  But if you do what I suggest above, you can just drop
this whole bit and not worry about it.

Regards,

Anthony Liguori

>              case QEMU_OPTION_usb:
>                  usb_enabled = 1;
> -- 
> 1.7.1
Jason Baron - Aug. 1, 2012, 6:28 p.m.
On Wed, Aug 01, 2012 at 01:21:57PM -0500, Anthony Liguori wrote:
> Jason Baron <jbaron@redhat.com> writes:
> 
> > 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 <jbaron@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) {
> 
>     machine_opts = qemu_opts_find(qemu_find_opts("machine"), 0);
>     if (machine_opts && qemu_opt_get_bool(machine_opts, "dump-guest-core")) {
> 

should be:
 
... && !qemu_opt_get_bool(machine_opts, "dump-guest-core", true)

??

> > +        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",
> 
> "dump-guest-core"
> 

ok.

> > +            .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;
> 
> Drop the globals.
> 

ok.

> >  
> >  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;
> 
> The -machine option is not the only way to set machine options so this
> is incorrect.  But if you do what I suggest above, you can just drop
> this whole bit and not worry about it.
> 

ok. oops.

Thanks,

-Jason
Anthony Liguori - Aug. 1, 2012, 6:54 p.m.
Jason Baron <jbaron@redhat.com> writes:

> On Wed, Aug 01, 2012 at 01:21:57PM -0500, Anthony Liguori wrote:
>> Jason Baron <jbaron@redhat.com> writes:
>> 
>> > 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 <jbaron@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) {
>> 
>>     machine_opts = qemu_opts_find(qemu_find_opts("machine"), 0);
>>     if (machine_opts && qemu_opt_get_bool(machine_opts, "dump-guest-core")) {
>> 
>
> should be:
>  
> ... && !qemu_opt_get_bool(machine_opts, "dump-guest-core", true)
>
> ??

Yes.

Regards,

Anthony Liguori
Luiz Capitulino - Aug. 2, 2012, 6:05 p.m.
On Wed, 01 Aug 2012 13:21:57 -0500
Anthony Liguori <anthony@codemonkey.ws> wrote:

> > 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",
> 
> "dump-guest-core"

Without your patch to accept both "-" and "_", this will be inconsistent
with the other options.

It's not like I mind too much, but then my patch adding mem-merge could
also be applied (Jan objected because of -/_ mixture).

Patch

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;