Re: [Qemu-devel] [PATCH v4 2/5] x86: Allow physical address bits to be set

[Paolo Bonzini <pbonzini@redhat.com>]

On 08/07/2016 20:59, Eduardo Habkost wrote:
> > +        if (env->features[FEAT_1_EDX] & CPUID_PSE36) {
> > +            cpu->phys_bits = 36;
> > +        } else {
> > +            cpu->phys_bits = 32;
> 
> But TCG_PHYS_ADDR_BITS is still 36. Does this mean TCG
> reserved-bit handling is broken if pse36 is disabled?

This makes sense as a default, apparently if you don't have PSE36 but 
you have phys_bits > 32, Windows complains:

    commit 45fd08effd461f85d0480d3b8f85a07751fc55b3
    Author: aurel32 <aurel32@c046a42c-6fe2-441c-8c8c-71466251a162>
    Date:   Tue Oct 14 19:20:52 2008 +0000

    target-i386: Add Core Duo Definition
    
    This patch adds a CPU definition for the Core Duo CPU. I tried to
    resemble the original as closely as possible and document what features
    are missing still. This patch enables the use of a recent CPU definition
    on 32 bit platforms.
    
    It also fixes two issues that went along the line:
    
    - invalid xlevel in core2duo spec
      While looking though the CPUIDs again, I found that xlevel is actually 8.
    
    - non-PSE36 support
      The CoreDuo CPUID does not expose the PSE36 capability, but CPUID
    0x80000008 is tied to 36 bits. This broke Windows XP installation for
    me, so I just set it to 32 bits width when PSE36 is not available. The
    original CPU also exposes 32 bit width in CPUID 0x80000008.
    
    Signed-off-by: Alexander Graf <agraf@suse.de>
    Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
    
    git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5488 c046a42c-6fe2-441c-8c8c-71466251a162

As long as it's overridable I guess it's fine...

Paolo