lkml.org 
[lkml]   [2017]   [Dec]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v3 00/27] kill devm_ioremap_nocache
From
Date
hi Christophe and Greg,

On 2017/12/24 16:55, christophe leroy wrote:
>
>
> Le 23/12/2017 à 16:57, Guenter Roeck a écrit :
>> On 12/23/2017 05:48 AM, Greg KH wrote:
>>> On Sat, Dec 23, 2017 at 06:55:25PM +0800, Yisheng Xie wrote:
>>>> Hi all,
>>>>
>>>> When I tried to use devm_ioremap function and review related code, I found
>>>> devm_ioremap and devm_ioremap_nocache is almost the same with each other,
>>>> except one use ioremap while the other use ioremap_nocache.
>>>
>>> For all arches? Really? Look at MIPS, and x86, they have different
>>> functions.
>>>
>>
>> Both mips and x86 end up mapping the same function, but other arches don't.
>> mn10300 is one where ioremap and ioremap_nocache are definitely different.
>
> alpha: identical
> arc: identical
> arm: identical
> arm64: identical
> cris: different <==
> frv: identical
> hexagone: identical
> ia64: different <==
> m32r: identical
> m68k: identical
> metag: identical
> microblaze: identical
> mips: identical
> mn10300: different <==
> nios: identical
> openrisc: different <==
> parisc: identical
> riscv: identical
> s390: identical
> sh: identical
> sparc: identical
> tile: identical
> um: rely on asm/generic
> unicore32: identical
> x86: identical
> asm/generic (no mmu): identical

Wow, that's correct, sorry for I have just checked the main archs, I means
x86,arm, arm64, mips.

However, I stall have no idea about why these 4 archs want different ioremap
function with others. Drivers seems cannot aware this? If driver call ioremap
want he really want for there 4 archs, cache or nocache?

>
> So 4 among all arches seems to have ioremap() and ioremap_nocache() being different.
>
> Could we have a define set by the 4 arches on which ioremap() and ioremap_nocache() are different, something like HAVE_DIFFERENT_IOREMAP_NOCACHE ?

Then, what the HAVE_DIFFERENT_IOREMAP_NOCACHE is uesed for ?

Thanks
Yisheng
>
> Christophe
>
>>
>> Guenter
>>
>>>> While ioremap's
>>>> default function is ioremap_nocache, so devm_ioremap_nocache also have the
>>>> same function with devm_ioremap, which can just be killed to reduce the size
>>>> of devres.o(from 20304 bytes to 18992 bytes in my compile environment).
>>>>
>>>> I have posted two versions, which use macro instead of function for
>>>> devm_ioremap_nocache[1] or devm_ioremap[2]. And Greg suggest me to kill
>>>> devm_ioremap_nocache for no need to keep a macro around for the duplicate
>>>> thing. So here comes v3 and please help to review.
>>>
>>> I don't think this can be done, what am I missing? These functions are
>>> not identical, sorry for missing that before.

Never mind, I should checked all the arches, sorry about that.

>>>
>>> thanks,
>>>
>>> greg k-h
>>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
> ---
> L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
> https://www.avast.com/antivirus
>
>
> .
>

\
 
 \ /
  Last update: 2017-12-25 02:10    [W:0.066 / U:11.908 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site