[Xen-users] Xen GPL PV and undesirable requirement for APIC (irq > 15)

["Oliver Wilcock" <oliver@xxxxxxx>]

Hi James,

Thanks for all the hard work on the GPL PV project.

I've been having trouble with the more recent builds and then saw this:

> Making Windows do the right thing with IRQ's etc was really hard, I
tried quite a few different approaches and this was the best one I could
come up with. It is a pity that it doesn't work with apic=0, but I don't
think that there is a valid reason these days why you would set apic=0.
Previously (xen 3.0.x) it was required to make some versions of windows
work.
>
> James

The APIC problems haven't gone away, as far as I'm aware...


Like a number of people I run my Windows HVMs with apic=0 (or rather with
the "Standard PC" hal.dll or halacpi.dll) to avoid performance problems.

Earlier releases of the GPL PV drivers worked well with "Standard PC" and
Windows XP halacpi.dll , but in the last few weeks they have been
unusable.

I just wanted to express my concern about the idea that the xennet driver
should crash if used with a non APIC HAL.  The xennet driver should work
with any HAL, just like the xenvbd driver.

It would be nice if the apic problems were fixed, too.  Any idea why the
APIC related problem?  I think the pre-requisites for the symptoms are AMD
CPU and 64 bit hypervisor and 32 bit Windows HVM.

reference:
http://forums.novell.com/novell-product-support-forums/suse-linux-enterprise-server-sles/sles-virtualization/337603-win2k3-xp-poor-performance-eats-10-cpu-while-idle.html



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