On Wed, Aug 01, 2012 at 01:21:57PM -0500, Anthony Liguori wrote:
> Jason Baron <jba...@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 <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) {
>
> 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
