Re: [Qemu-devel] [PATCH] fix guest physical bits to match host, to go beyond 1TB guests

[Paolo Bonzini]

Il 16/07/2013 20:11, Eduardo Habkost ha scritto:
> For physical bit size, what about extending it in a backwards-compatible
> way? Something like this:
> 
>     *eax = 0x0003000; /* 48 bits virtual */
>     if (ram_size < 1TB) {
>         physical_size = 40; /* Keeping backwards compatibility */
>     } else if (ram_size < 4TB) {
>         physical_size = 42;

Why not go straight up to 44?

>     } else {
>         abort();
>     }
>     if (supported_host_physical_size() < physical_size) {
>         abort();
>     }
>     *eax |= physical_size;
> 
> (Of course, the abort() calls should be replaced with proper error
> reporting)

This makes sense too.  Though the best would be of course to use CPUID
values coming from the real processors, and only using 40 for backwards
compatibility.

Paolo