From: gang.chen@asianux•com (Chen Gang)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 2/2] ARM: include: asm: use 'int' instead of 'unsigned long' for normal register variables within atomic.h
Date: Tue, 01 Oct 2013 20:03:44 +0800 [thread overview]
Message-ID: <524ABA20.6060106@asianux.com> (raw)
In-Reply-To: <20131001090119.GA17629@mudshark.cambridge.arm.com>
On 10/01/2013 05:01 PM, Will Deacon wrote:
> On Tue, Oct 01, 2013 at 03:05:27AM +0100, Chen Gang wrote:
>> On 10/01/2013 12:11 AM, Will Deacon wrote:
>>> On Sun, Sep 29, 2013 at 04:52:28AM +0100, Chen Gang wrote:
>>>> "arc/arm" will be never on 64-bit, it is mainly on 32-bit (may also can
>>>> be on 16-bit).
>>>>
>>>> So better to use 'int' instead of 'unsigned long' for normal register
>>>> variable (on 16-bit, 'int' is allowed to be 16-bit, so historically,
>>>> often use 'int' for normal register variables).
>>>
>>> This commit message doesn't make a blind bit of sense! arch/arm/ is a 32-bit
>>> architecture in the sense that int will always be 32-bit there. This patch
>>> is just a cosmetic change, bringing our atomic_t manipulation code inline
>>> with the atomic_t type definition.
>>>
>>
>> OK, thanks. That means: "arm means arm 32-bit, arm64 means arm 64-bit.
>> The current Linux kernel main line does not support arm 16-bit".
>>
>> Since "bringing our atomic_t ... with the atomic_t type definition", can
>> we use 'atomic_t" instead of 'unsigned long'?
>>
>> And can we use 'atomic64_t" instead of 'unsigned long' in atomic64_*()?
>
> That's probably a bit dodgy, since they are typedefs to compound types
> which, if ever extended, would fall to bits if we tried to pack them into a
> single register.
>
Excuse me, my English is not quite well, I guess your meaning is: "in
'atomic.h', for arm/arm64, let register variables type equal to related
atomic type: use 64-bit type if 'atomic64_t', 32-bit type if 'atomic_t'.
If what I guess is correct, please continue reading, or please help
repeat again (not need reading below contents), thanks.
Can we say: "under arm, using 'unsigned long' for register related
variables in atomic64_*() is not suitable (although not a bug), need use
'long long' (which is 'atomic64_t' under arm) instead of"?
And under arm64, can we use 'int' (which is 'atomic_t' under 64-bit arm)
instead of 'unsigned long' for register related variables in atomic_*()?
I feel, if both of them above are correct, your idea sounds reasonable,
or it seems your idea is a little complex (at least, keeping original
implementation no touch is still not a bad idea).
> Will
>
>
Thanks.
--
Chen Gang
next prev parent reply other threads:[~2013-10-01 12:03 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-21 11:06 [PATCH] ARM: include: asm: atomic.h: use type cast 's64' for the return value of atomic64_add_return() Chen Gang
2013-09-24 9:30 ` Will Deacon
2013-09-24 10:27 ` Russell King - ARM Linux
2013-09-24 10:37 ` Chen Gang
2013-09-24 10:30 ` Chen Gang
2013-09-25 2:25 ` [PATCH v2] ARM: include: asm: use 'long long' instead of 'u64' within atomic.h Chen Gang
2013-09-25 16:07 ` Will Deacon
2013-09-26 2:00 ` Chen Gang
2013-09-26 10:04 ` Will Deacon
2013-09-26 11:03 ` Chen Gang
2013-09-27 11:06 ` Will Deacon
2013-09-27 11:36 ` Chen Gang
2013-09-29 3:43 ` [PATCH 0/2] ARM: include: asm: change functions' and variables' types in atomic.h Chen Gang
2013-09-29 3:43 ` [PATCH 1/2] ARM: include: asm: use 'long long' instead of 'u64' within atomic.h Chen Gang
2013-09-29 3:52 ` [PATCH 2/2] ARM: include: asm: use 'int' instead of 'unsigned long' for normal register variables " Chen Gang
2013-09-30 16:11 ` Will Deacon
2013-10-01 2:05 ` Chen Gang
2013-10-01 9:01 ` Will Deacon
2013-10-01 12:03 ` Chen Gang [this message]
2013-10-02 10:41 ` Will Deacon
2013-10-02 15:19 ` Chen Gang
2013-10-03 10:05 ` Chen Gang
2013-10-03 16:32 ` Will Deacon
2013-10-04 9:51 ` Chen Gang
2013-10-04 15:37 ` Will Deacon
2013-10-04 15:42 ` Will Deacon
2013-10-04 23:55 ` Chen Gang
2013-10-05 0:11 ` Chen Gang
2013-10-08 4:10 ` Chen Gang
2013-10-08 10:34 ` Will Deacon
2013-10-08 10:56 ` [PATCH v2 0/2] ARM: include: asm: change functions' and variables' types in atomic.h Chen Gang
2013-10-08 10:57 ` [PATCH v2 1/2] ARM: include: asm: use 'long long' instead of 'u64' within atomic.h Chen Gang
2013-10-08 10:59 ` [PATCH v2 2/2] ARM: include: asm: use 'int' instead of 'unsigned long' for 'oldval' in atomic_cmpxchg() Chen Gang
2013-10-09 10:48 ` Will Deacon
2013-10-10 0:56 ` Chen Gang
2013-10-09 10:46 ` [PATCH v2 1/2] ARM: include: asm: use 'long long' instead of 'u64' within atomic.h Will Deacon
2013-10-08 11:00 ` [PATCH 2/2] ARM: include: asm: use 'int' instead of 'unsigned long' for normal register variables " Chen Gang
2013-10-08 10:33 ` Will Deacon
2013-10-08 11:29 ` Chen Gang
2013-10-08 17:49 ` Will Deacon
2013-10-09 0:18 ` Chen Gang
2013-10-09 1:22 ` Chen Gang
2013-09-30 16:07 ` [PATCH 1/2] ARM: include: asm: use 'long long' instead of 'u64' " Will Deacon
2013-10-01 2:09 ` Chen Gang
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