Commit ddb97f1d authored by Jason Baron's avatar Jason Baron Committed by Anthony Liguori
Browse files

memory: add -machine dump-guest-core=on|off 



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.

Is anything additional required to preserve this setting for migration or
savevm? I don't believe so.

Changelog:
v3:
    Eliminate globals as per Anthony's suggestion
    set no dump from qemu_ram_remap() as well
v2:
    move the option from -m to -machine, rename option dump -> dump-guest-core

Signed-off-by: default avatarJason Baron <jbaron@redhat.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent 3c4a4d0d

exec.c

+21 −0
Original line number Diff line number Diff line
@@ -2475,6 +2475,24 @@ static ram_addr_t last_ram_offset(void) 
    return last;

}



static void qemu_ram_setup_dump(void *addr, ram_addr_t size)

{

    int ret;

    QemuOpts *machine_opts;



    /* Use MADV_DONTDUMP, if user doesn't want the guest memory in the core */

    machine_opts = qemu_opts_find(qemu_find_opts("machine"), 0);

    if (machine_opts &&

        !qemu_opt_get_bool(machine_opts, "dump-guest-core", true)) {

        ret = qemu_madvise(addr, size, QEMU_MADV_DONTDUMP);

        if (ret) {

            perror("qemu_madvise");

            fprintf(stderr, "madvise doesn't support MADV_DONTDUMP, "

                            "but dump_guest_core=off specified\n");

        }

    }

}



void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev)

{

    RAMBlock *new_block, *block;
@@ -2554,6 +2572,8 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host, 
           0, size >> TARGET_PAGE_BITS);

    cpu_physical_memory_set_dirty_range(new_block->offset, size, 0xff);



    qemu_ram_setup_dump(new_block->host, size);



    if (kvm_enabled())

        kvm_setup_guest_memory(new_block->host, size);
@@ -2670,6 +2690,7 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length) 
                    exit(1);

                }

                qemu_madvise(vaddr, length, QEMU_MADV_MERGEABLE);

                qemu_ram_setup_dump(vaddr, length);

            }

            return;

        }

osdep.h

+7 −0
Original line number Diff line number Diff line
@@ -103,6 +103,11 @@ 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)
@@ -110,6 +115,7 @@ 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 */
@@ -117,6 +123,7 @@ 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

qemu-config.c

+4 −0
Original line number Diff line number Diff line
@@ -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 */ }

    },

qemu-options.hx

+4 −1
Original line number Diff line number Diff line
@@ -37,7 +37,8 @@ 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}[,...]]
@@ -54,6 +55,8 @@ 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