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: Jason Baron <jbaron@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/exec.c b/exec.c
index 929db5c..5834766 100644
--- a/exec.c
+++ b/exec.c
@@ -2475,6 +2475,24 @@
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 @@
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 @@
exit(1);
}
qemu_madvise(vaddr, length, QEMU_MADV_MERGEABLE);
+ qemu_ram_setup_dump(vaddr, length);
}
return;
}
