(2013/11/20 7:19), Andi Kleen wrote:
So I wanted to use crash to look at a dump from a qemu KVM guest
I write a dump file from the qemu console with
dump-guest-core foo
Hello,
If you want a crash dump of the running qemu guest machine,
you can use dump-guest-memory command.
ETEXI
{
.name = "dump-guest-memory",
.args_type = "paging:-p,filename:F,begin:i?,length:i?",
.params = "[-p] filename [begin] [length]",
.help = "dump guest memory to file"
"\n\t\t\t begin(optional): the starting physical address"
"\n\t\t\t length(optional): the memory size, in bytes",
.mhandler.cmd = hmp_dump_guest_memory,
},
STEXI
@item dump-guest-memory [-p] @var{protocol} @var{begin} @var{length}
@findex dump-guest-memory
Dump guest memory to @var{protocol}. The file can be processed with crash or
gdb.
filename: dump file name
paging: do paging to get guest's memory mapping
begin: the starting physical address. It's optional, and should be
specified with length together.
length: the memory size, in bytes. It's optional, and should be specified
with begin together.
BTW, I heard the dump-guest-core command for the first time.
According to the source code, it looks like the command to decide whether
or not to include VM guest in a process core dump generated by KVM
host kernel.
static void qemu_ram_setup_dump(void *addr, ram_addr_t size)
{
int ret;
/* Use MADV_DONTDUMP, if user doesn't want the guest memory in the core */
if (!qemu_opt_get_bool(qemu_get_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");
}
}
}
According to qemu-ptions.hx, syntax of the command is:
@item dump-guest-core=on|off
Include guest memory in a core dump. The default is on.
So, it seems strange to me that the fact "foo" file was generated...
--
Thanks.
HATAYAMA, Daisuke
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