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")) {
> + 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
