Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
> On 4/2/23 16:10, Bernhard Beschow wrote:
>> Treat the smram MemoryRegion analoguous to other memory regions such as
>> ram, pci, io, ... , making the used memory regions more explicit when
>> instantiating q35 or i440fx.
>> Note that the q35 device uses these memory regions only during the
>> realize phase which suggests that it shouldn't be the owner of smram.
>
> Few years ago I tried something similar and it wasn't accepted because
> the MR owner name is used in the migration stream, so this was breaking
> migrating from older machines.
I don't remember the details O:-)
Migration code, really depends on RAMBlocks names, not memory region
names. But as far as I remember, that don't matter too much because the
memory region names ends tangled quite a bit with the RAMBlock name, right?
> Adding David/Juan for double-checking that.
trace_vmstate_save(se->idstr, se->vmsd ? se->vmsd->name : "(old)");
You can try to enable this trace and see that every section has the same
name with and without your change (i.e. that memory region name is not
seen by the migration stream).
But that is the only help that I can came with.
The code that you are changing (smram) is something that I don't know
about to give you more help.
Looking at the patch, it looks that the name was before and now the
"sram", so perhaps it could help. But I don't know.
In the i440fx you say that you only use it until realize, so you should
be safe.
For q35, it is not clear to me.
If the trace don't show new names, I will just try:
- migrate a i440fx machine from binary without your patch to one with
your patch
- the same for q35.
And depending on the result, we can go from there.
Thanks for the pointers, Juan!
I took some inspiration and created four migration files, {pc,q35}-{before,after}.mig by running `qemu-system-x86_64 -M {pc,q35} -S` with qemu built from master and from my branch. Then I basically ran `./scripts/analyze-migration.py -d desc -f *.mig > *.json` on the four files and compared the diffs. Both diffs were empty. AFAIU this proves that there is no binary change, right?
Best regards,
Bernhard
Later, Juan.