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SubjectRe: [PATCH v10 11/12] x86, mm, pat: Refactor !pat_enabled handling
On Wed, May 27, 2015 at 09:19:03AM -0600, Toshi Kani wrote:
> This patch refactors the !pat_enabled code paths and integrates

Please refrain from using such empty phrases like "This patch does this
and that" in your commit messages - it is implicitly obvious that it is
"this patch" when one reads it.

> them into the PAT abstraction code. The PAT table is emulated by
> corresponding to the two cache attribute bits, PWT (Write Through)
> and PCD (Cache Disable). The emulated PAT table is the same as the
> BIOS default setup when the system has PAT but the "nopat" boot
> option is specified. The emulated PAT table is also used when
> MSR_IA32_CR_PAT returns 0 (9d34cfdf4).

9d34cfdf4 - what is that thing? A commit message? If so, we quote them
like this:

9d34cfdf4796 ("x86: Don't rely on VMWare emulating PAT MSR correctly")

note the 12 chars length of the commit id.

> Signed-off-by: Toshi Kani <toshi.kani@hp.com>
> Reviewed-by: Juergen Gross <jgross@suse.com>
> ---
> arch/x86/mm/init.c | 6 ++--
> arch/x86/mm/iomap_32.c | 12 ++++---
> arch/x86/mm/ioremap.c | 10 +-----
> arch/x86/mm/pageattr.c | 6 ----
> arch/x86/mm/pat.c | 77 +++++++++++++++++++++++++++++-------------------
> 5 files changed, 57 insertions(+), 54 deletions(-)

So I started applying your pile and everything was ok-ish until I came
about this trainwreck. You have a lot of changes in here, the commit
message is certainly lacking sufficient explanation as to why and this
patch is changing stuff which the previous one adds.

So a lot of unnecesary code movement.

Then you have stuff like this:

+ } else if (!cpu_has_pat && pat_enabled) {

How can a CPU not have PAT but have it enabled?!?

So this is not how we do patchsets.

Please do the cleanups *first*. Do them in small, self-contained changes
explaining *why* you're doing them.

*Then* add the new functionality, .i.e. the WT.

Oh, and when you do your next version, do the patches against tip/master
because there are a bunch of changes in the PAT code already.

Thanks.

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.
--


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