From: felipe.contreras@gmail.com (Felipe Contreras)
To: linux-arm-kernel@lists.infradead.org
Subject: 'bx lr' vs 'mov pc,lr'
Date: Mon, 14 Sep 2009 03:11:23 +0300 [thread overview]
Message-ID: <94a0d4530909131711p63dabe95j3cff160e2656bb69@mail.gmail.com> (raw)
In-Reply-To: <20090913230103.GD30169@n2100.arm.linux.org.uk>
On Mon, Sep 14, 2009 at 2:01 AM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Mon, Sep 14, 2009 at 01:56:16AM +0300, Felipe Contreras wrote:
>> On Mon, Sep 14, 2009 at 1:15 AM, Daniel Silverstone
>> <dsilvers@simtec.co.uk> wrote:
>> > On Mon, Sep 14, 2009 at 12:55:24AM +0300, Felipe Contreras wrote:
>> >> I noticed that in 'arch/arm/lib/delay.S' we are using 'mov pc, lr'
>> >> instead of 'bx lr'. Why? It looks like 'mov pc, lr' is used all over
>> >> the place, but I can't find out what's the reason.
>> >
>> > I'd guess at the reason being that not all ARM processors whose ports use
>> > arch/arm/lib/delay.S support the bx instruction, whereas the 'mov pc, lr'
>> > instruction is universally supported.
>>
>> Are there really processors that don't support 'bx'? Can you give some examples?
>
> Any ARMv3 CPU and any ARMv4 which doesn't support Thumb. ?Eg, StrongARM.
Ok. Thanks.
--
Felipe Contreras
next prev parent reply other threads:[~2009-09-14 0:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-13 21:55 'bx lr' vs 'mov pc,lr' Felipe Contreras
2009-09-13 22:15 ` Daniel Silverstone
2009-09-13 22:56 ` Felipe Contreras
2009-09-13 23:01 ` Russell King - ARM Linux
2009-09-14 0:11 ` Felipe Contreras [this message]
2009-09-13 22:58 ` Russell King - ARM Linux
2009-09-14 0:11 ` Felipe Contreras
2009-09-14 0:20 ` Jamie Lokier
2009-09-14 1:47 ` Felipe Contreras
2009-09-14 7:35 ` Uwe Kleine-König
2009-09-14 12:59 ` Felipe Contreras
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