Re: [PATCH 2/5] x86: PAT: fix ambiguous paranoia check in pat_init()

[Rene Herman]

On 10-06-08 16:05, Andreas Herrmann wrote:

> Starting with commit 8d4a4300854f3971502e81dacd930704cb88f606 (x86:
> cleanup PAT cpu validation) the PAT CPU feature flag is not cleared
> anymore. Now the error message
>
>   "PAT enabled, but CPU feature cleared"
>
> in pat_init() is misleading.

No, it's correct. This is to be read as "The PAT feature is enabled in 
the kernel but the CPU claims to not have PAT". The message is not a 
leftover from the old flag-clearing setup or anything; it was introduced 
in the patch that disabled that.

> Furthermore the current code does not check for existence of the PAT
> CPU feature flag if a CPU is whitelisted in validate_pat_support.

Which is okay-ish, or at least by design it seems. The paranoia check in 
pat.c will catch this case.

The current setup is okay really. The only thing it still wants is a 
commandline whitelist switch but that needs a somewhat different setup 
as validate_pat_support() is too early for __setup() or early_param().

Rene.
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