From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andre Przywara <andre.przywara@amd.com>
Subject: Re: [PATCH 3/5] xl: implement parsing of cpuid
 parameter and translate to Xen interface
Date: Thu, 16 Sep 2010 20:49:08 +0200
Message-ID: <4C9266A4.1020905@amd.com>
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To: Ian Campbell <Ian.Campbell@eu.citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>, Keir Fraser <Keir.Fraser@eu.citrix.com>, Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>
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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