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Date: Wed, 05 Nov 2008 13:59:53 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH] compile x86_64 on i386
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To: qemu-devel@nongnu.org

Glauber Costa wrote:
> On Wed, Nov 5, 2008 at 5:13 PM, Anthony Liguori <anthony@codemonkey.ws> wrote:
>   
>> Glauber Costa wrote:
>>     
>>> This patch allows qemu-system-x86_64 to be compiled on a i386 host.
>>>
>>>       
>> For this to properly work, you need to fix the FIXMEs in target-i386/kvm.c
>> that are around lm_capable_check.  Basically, if you're on a 32-bit kernel,
>> but a 64-bit capable processor, you need to mask long mode from the guest or
>> it may try to use it.
>>     
>
> Yes, but 32-bit kernels work fine (since they not even try)
> So they are orthogonal.
>   

Well, I don't buy your argument, but we have the same problem with 
qemu-system-i386 anyway so I guess your patch makes things no worse.

I've committed something slightly different that I hope will extend more 
easily.  Thanks.

Regards,

Anthony Liguori

>> Regards,
>>
>> Anthony Liguori
>>
>>     
>>> ---
>>>  configure |   17 ++++++++++-------
>>>  1 files changed, 10 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/configure b/configure
>>> index 067c3c5..65f0c74 100755
>>> --- a/configure
>>> +++ b/configure
>>> @@ -1447,13 +1447,16 @@ interp_prefix1=`echo "$interp_prefix" | sed
>>> "s/%M/$target_cpu/g"`
>>>  echo "#define CONFIG_QEMU_PREFIX \"$interp_prefix1\"" >> $config_h
>>>  gdb_xml_files=""
>>>  -# FIXME allow i386 to build on x86_64 and vice versa
>>> -if test "$kvm" = "yes" -a "$target_cpu" != "$cpu" ; then
>>> -  kvm="no"
>>> -fi
>>> -# Disable KVM for linux-user
>>> -if test "$kvm" = "yes" -a "$target_softmmu" = "no" ; then
>>> -  kvm="no"
>>> +if test "$kvm" = "yes";
>>> +then
>>> +  # Disable KVM for linux-user
>>> +  if test "$target_softmmu" = "no";
>>> +  then
>>> +     kvm="no"
>>> +  elif test "$target_cpu" != "$cpu" && test ! "$cpu" = "i386" -a
>>>  "$target_cpu" = "x86_64" ;
>>> +  then
>>> +        kvm="no"
>>> +  fi
>>>  fi
>>>   case "$target_cpu" in
>>>
>>>       
>>
>>
>>     
>
>
>
>