Re: [Qemu-devel] [PATCH v3 0/7] Let boards state maximum RAM limits in QEMUMachine struct

[Jes Sorensen <Jes.Sorensen@redhat.com>]

On 04/04/11 19:26, Peter Maydell wrote:
> On 4 April 2011 15:53, Jes Sorensen <Jes.Sorensen@redhat.com> wrote:
>> I understand that what you are proposing seems to work well enough for
>> your problem at hand. What I am saying is that adding a mechanism like
>> that, can cause problems for adding a more generic mechanism that
>> handles more advanced boards in the future. I much prefer a generic
>> solution than a simple hack.
> 
> I don't think it's a hack. I think it's a reasonably clean solution
> to the set of cases we've actually encountered in practice, and I
> think trying to design something more generalised without actually
> having a use case to tie it to is just going to produce something
> complicated which doesn't turn out to actually be what a hypothetical
> "advanced board" will actually need. I think we're much better off
> with code that does what we need it to do now, and designing
> and implementing the complicated generic framework only when we
> actually need it.

Sorry but it is not a clean solution at all, it's a simple hack based on
a linear model, which happens to work in practice when dealing with some
simple boards. I suggested a very simple interface that would work fine
for embedded boards, and which would be simple to implement.

The so called advanced boards you're referring to are out there in
numbers already, you probably have a couple of them. They are called PCs.

>> As I pointed out before, this is not a theoretical problem, most numa
>> systems have this issue, including many x86 boxes. I can see the problem
>> also existing with mips boards like the sb1250 ones I worked on many
>> years ago.
> 
> OK, so presumably you can provide a qemu command line and an image
> which demonstrates the problem...

Look at the -numa argument and show me the code that actually validates
the memory amount correctly in that case?

Jes