On 05/16/14 15:01, Jun Koi wrote:
>
>
>
> On Fri, May 16, 2014 at 7:30 PM, Laszlo Ersek <ler...@redhat.com
> <mailto:ler...@redhat.com>> wrote:
>
> On 05/16/14 11:59, Jun Koi wrote:
>
> > - is it true that dump-guest-memory just write down physical memory
> > page, and does not consider the virtual-memory concept?
>
> No, it isn't.
>
> Basically, "dump-guest-memory" supports two modes of operation, "paging
> enabled" and "paging disabled".
>
> Many (most?) people dump for the "crash" utility, which is super smart,
> and extra paging info is not needed. For "crash" we just dump the
> guest-phys memory ranges the way the guest sees them, and that's it;
> "crash" figures out everything from that.
>
> If you want to use "gdb" rather than "crash", or need the guest-virtual
> addresses in the ELF vmcore for some other reason, then you should
> invoke "dump-guest-memory" with paging enabled.
>
> Enter "help dump-guest-memory" at the qemu monitor prompt, and look for
> the "-p" option.
>
>
> so i suppose this works for all kind of OS in guest VM, not only Linux
> guest?
far as I remember, it should; the virtual mappings "in effect" are
searched starting from cr3:
qmp_dump_guest_memory() [dump.c]
dump_init()
qemu_get_guest_memory_mapping() [memory_mapping.c]
for (almost) all VCPUs:
cpu_get_memory_mapping() [qom/cpu.c]
x86_cpu_get_memory_mapping()
[target-i386/arch_memory_mapping.c]
check cr3, cr4; walk page tables etc
There are some caveats / limitations: search "qapi-schema.json" for the
string "dump-guest-memory", and read that section.
Laszlo
