[Xen-devel] Re: [PATCH 3/5] xl: implement parsing of cpuid parameter and translate to Xen interface

[Andre Przywara <andre.przywara@xxxxxxx>]

Ian Campbell wrote:
> On Thu, 2010-09-16 at 14:08 +0100, Andre Przywara wrote:
> > Parses a string enumerating cpuid flags and their behavior.
> > The syntax is: cpuid = "host,<flagname>=[01xks],..."
> > Supports:
> > 0: clear this flag
> > 1: set this flag
> > x: don't care, use the default handling
> > k: use the host value
> > s: as k, but keep stable across migrations
> >
> > Instead of the bits there can also be numbers passed (hex or dec),
> > like: family=0x10,model=4
> Isn't this ambiguous?
No, since I don't support this legacy multi-bit syntax in the new 
format. I cannot think of a use-case for "keep the third bit in the 
family number".
The above characters are just for single bit flags. Multi-bit flags need 
a number or a single character that gets multiplied ([xks]). The patch 
description is a bit vague in this respect, I will fix it with a 
documentation patch later.
Thanks for looking closely!

Regards,
Andre.

> 0x10 could be a hex number (i.e. 16 decimal) but it could be "(0) clear,
> (x) don't care, (1) set, (0) clear". (i.e. either 2 or 6 depending on
> the eventual value for the don't care)
>
> Ian.
--
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 448-3567-12


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