lkml.org 
[lkml]   [2014]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v8 4/4] qrwlock: Use smp_store_release() in write_unlock()
On Tue, Jan 14, 2014 at 3:03 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Tue, Jan 14, 2014 at 10:28:23AM +0800, Daniel J Blueman wrote:
>> >Peter,
>> >
>> >I found out that the build failure was caused by the fact that the
>> >__native_word() macro (used internally by compiletime_assert_atomic())
>> >allows only a size of 4 or 8 for x86-64. The data type that I used is a
>> >byte. Is there a reason why byte and short are not considered native?
>>
>> It seems likely it was implemented like that since there was no existing
>> need; long can be relied on as the largest native type, so this should
>> suffice and works here:
>
> There's Alphas that cannot actually atomically adres a byte; I do not
> konw if Linux cares about them, but if it does, we cannot in fact rely
> on this in generic primitives like this.

That's right, and thanks for the heads-up. Alpha can only address 4
and 8 bytes atomically. (LDL_L, LDQ_L, STL_C, STQ_C).

The Byte-Word extension in EV56 doesn't add new atomics, so in fact no
Alphas can address < 4 bytes atomically.


\
 
 \ /
  Last update: 2014-01-14 19:01    [W:1.436 / U:0.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site