On Wed, 25 Feb 2009 14:15:37 +0100
Thorsten Leemhuis <fedora(a)leemhuis.info> wrote:
On 25.02.2009 13:27, Chris Lalancette wrote:
> Gerd Hoffmann wrote:
>> We can also simply do this:
>>
>> - Install PAE kernel if the CPU supports PAE.
>>
>> i.e. make PAE the default kernel.
>
> Yes, I really think we should just do this. It's simple, it means we get the
> logic right for Xen as well as bare-metal (without any special cases), and the
> performance hit for those who have PAE and < 4GB isn't that bad, I don't
think
> (although numbers one way or the other would be interesting to see).
What about compatibility problems? My old laptop had a PAE capable CPU
but could not boot a PAE kernel -- I noticed when I was trying a PAE
kernel for some tests two or three years ago. I asked a kernel-developer
back then if it was worth reporting and I got told that such problems
are not unusual and often BIOS or hardware problems. Those likely didn't
vanish magically is that statement is correct.
The algorithm I posted should handle that. If you support NX or you have >4GB
of memory then it's pretty much impossible for you to have one of those old CPUs.
And all SVM/VMX capable machines support NX so we'd always have the right kernel
for them too.