Re: [Qemu-devel] [PATCH 2/5] exec: qemu_ram_alloc_device, qemu_ram_resize

[Juan Quintela <quintela@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 19/11/2014 14:57, Juan Quintela wrote:
>> > Shipping a separate BIOS for different machine types is unrealistic and
>> > pointless.  It would also be a good terrain for bug reports, unless you
>> > also do things like "forbid creating -device megasas-gen2 on 2.1 because
>> > it was introduced in 2.2".
>>
>> And I agree with that.  If it got introduced on 2.2, it should not be
>> allowed on pc-2.1.  It just makes things more complicated.  We don't
>> have infrastructure to enforce that.  And I am claining that is the
>> problem.  We are just papering over this problem each time that it
>> happens.  I honestely think that the only way to really fix
>> compatibility is enforcing that machine types are stable.  right now
>> they are now, and we ended nothing it.
>
> Weird, I have bought this USB device last month and I plugged it into a
> two-year-old laptop.
>
>     QEMU version = when did I last update firmware / buy hardware
>     Machine type = when did I buy the computer
>
> I honestly think that you are talking out of design dogma, without
> really thinking through the consequences of the design.

It is not the same, and you know it.
It is the equivalent: I have this aging pc with PCI and I have bought
this PCI-EXpress card, if I use enough force, perhaps it could work.

Enough force here would mean put some soldering here and there, new
chips, blah, blah, blah.  While the machine is running.  When you have a
different solution.  Powerdown machine.  Change machine type.  Boot it
again.  magic!!!!

It is not that I am not giving you one option to fix the problem, it is
a different solution.  Mine don't require changing anything, just forbid
something that now it is allowed, and that we have found difficult to
support.  I would jsut remove the claim that we support it.  I honestly
think that it is a good tradeof, and the only that we can guarantee.

Later, Juan.