linux-kernel - Re: [PATCH 1/3] powerpc/32: Fix hugepage allocation on 8xx at hint address

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Message-ID: <0e4e058e-db76-629c-c004-27e63b2cf9ab@c-s.fr>
Date:   Wed, 17 Jan 2018 10:47:07 +0100
From:   Christophe LEROY <christophe.leroy@....fr>
To:     "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Scott Wood <oss@...error.net>,
        Nicholas Piggin <npiggin@...il.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] powerpc/32: Fix hugepage allocation on 8xx at hint
 address



Le 17/01/2018 à 06:23, Aneesh Kumar K.V a écrit :
> Christophe LEROY <christophe.leroy@....fr> writes:
> 
>>>
>>>> How should I split in separate patches ? Something like ?
>>>> 1/ Slice support for PPC32 > 2/ Activate slice for 8xx
>>>
>>> Yes something like that. Will you  be able to avoid that
>>>    if (SLICE_NUM_HIGH) from the code? That makes the code ugly. Right now
>>> i don't have definite suggestion on what we could do though.
>>>
>>
>> Could use #ifdefs instead, but in my mind it would be even more ugly.
>>
>> I would have liked just doing nothing, but the issue is that at the
>> moment bitmap_xxx() functions are not prepared to handle bitmaps of size
>> zero. Should we try to change that ? Any chance to succeed ?
>>
> 
> How much code duplication it is to do slice_32.c?

Most functions use both .low_slices and .high_slices, so if your thought 
is to copy slice.c to slice_32.c and then remove all code handling 
.high_slices, we will at least duplicate 50% of the code

In v2 that I have just submitted, I have embedded this ugly test in 
macros called slice_bitmap_xxx() which handles the 0 nbits case. Tell me 
if it looks better that way.

Christophe

> 
> Michael,
> 
> What do you suggest here?
> 
> -aneesh
>