On Mon, Apr 08, 2019 at 04:42:13AM -0400, Catherine Ho wrote:
> Commit 18269069c310 ("migration: Introduce ignore-shared capability")
> addes ignore-shared capability to bypass the shared ramblock (e,g,
> membackend + numa node). It does good to live migration.
>
> As told by Yury,this commit expectes that QEMU doesn't write to guest RAM
> until VM starts, but it does on aarch64 qemu:
> Backtrace:
> 1 0x000055f4a296dd84 in address_space_write_rom_internal () at
> exec.c:3458
> 2 0x000055f4a296de3a in address_space_write_rom () at exec.c:3479
> 3 0x000055f4a2d519ff in rom_reset () at hw/core/loader.c:1101
> 4 0x000055f4a2d475ec in qemu_devices_reset () at hw/core/reset.c:69
> 5 0x000055f4a2c90a28 in qemu_system_reset () at vl.c:1675
> 6 0x000055f4a2c9851d in main () at vl.c:4552
>
> Actually, on arm64 virt marchine, ramblock "dtb" will be filled into ram
> druing rom_reset. In ignore-shared incoming case, this rom filling
> is not required since all the data has been stored in memory backend
> file.
>
> Further more, as suggested by Peter Xu, if we do rom_reset() now with
> these ROMs then the RAM data should be re-filled again too with the
> migration stream coming in.
>
> Fixes: commit 18269069c310 ("migration: Introduce ignore-shared
> capability")
> Suggested-by: Yury Kotov <yury-ko...@yandex-team.ru>
> Suggested-by: Peter Xu <pet...@redhat.com>
> Signed-off-by: Catherine Ho <catherine.h...@gmail.com>
Acked-by: Peter Xu <pet...@redhat.com>
--
Peter Xu
