On 06.02.20 12:28, Shameerali Kolothum Thodi wrote: > > >> -----Original Message----- >> From: David Hildenbrand [mailto:da...@redhat.com] >> Sent: 06 February 2020 10:56 >> To: Shameerali Kolothum Thodi <shameerali.kolothum.th...@huawei.com>; >> Igor Mammedov <imamm...@redhat.com> >> Cc: peter.mayd...@linaro.org; xiaoguangrong.e...@gmail.com; >> m...@redhat.com; shannon.zha...@gmail.com; qemu-devel@nongnu.org; >> xuwei (O) <xuw...@huawei.com>; Linuxarm <linux...@huawei.com>; >> eric.au...@redhat.com; qemu-...@nongnu.org; ler...@redhat.com >> Subject: Re: [PATCH v2 1/7] exec: Fix for qemu_ram_resize() callback > > [...] > >>> root@ubuntu:/# cat /dev/pmem >>> pmem0 pmem1 >>> >>> From the logs, it looks like the ram_load_precopy() --> qemu_ram_resize() is >> not >>> called as length == used_length and both seems to be page aligned values. >>> And from >> https://github.com/qemu/qemu/blob/master/migration/ram.c#L3421 >>> qemu_ram_resize() is called with length if length != used_length. >> >> Assume on your source, the old size is 12345 bytes. So 16384 aligned up >> (4 pages). >> >> Assume on your target, the new size is 123456 bytes, so 126976 aligned >> up (31 pages). >> >> If you migrate from source to destination, the migration code would >> resize to 16384, although the "actual size" is 12345. The callback will >> be called with the aligned size, not the actual size. Same the other way >> around. That's what's inconsistent IMHO. > > Thanks. You are right. I didn’t consider the case where the target can be > configured with a larger number of devices than the source. I can replicate > the scenario now, > > Source: > > fw_cfg_add_file_callback: filename etc/boot-fail-wait size 0x4 > fw_cfg_add_file_callback: filename etc/acpi/nvdimm-mem size 0x1000 > fw_cfg_add_file_callback: filename etc/acpi/tables size 0x6210 > > Target: > ram_load_precopy: Ram blk mem1 length 0x40000000 used_length 0x40000000 > ram_load_precopy: Ram blk virt.flash0 length 0x4000000 used_length 0x4000000 > ram_load_precopy: Ram blk virt.flash1 length 0x4000000 used_length 0x4000000 > ram_load_precopy: Ram blk /rom@etc/acpi/tables length 0x7000 used_length > 0x8000 > fw_cfg_modify_file: filename etc/acpi/tables len 0x7000 > > Target updates FWCfgEntry with a page aligned size :(. I will look into this > and see how > we can solve this. Any pointers welcome.
Can you look the original value up somehow and us the resize callback only as a notification that something changed? (that value would have to be stored somewhere and migrated I assume - maybe that's already being done) -- Thanks, David / dhildenb
