Automake question

[Sebastian Huber]

Ralf Corsepius wrote:
> On 07/29/2009 10:04 AM, Sebastian Huber wrote:
>> Ralf Corsepius wrote:
>>> On 07/29/2009 09:44 AM, Sebastian Huber wrote:
>>>> Hi,
>>>>
>>>> for a BSP I need to compile one module with non standard CFLAGS.
>>> Why? Under normal circumstances, you don't want to do this.
>>> In almost 100% of all cases, doing so is a bug.
>>>
>>> Ralf
>> On the ARMv4 architecture you have two instruction sets: ARM and THUMB.  I have
>> to compile one module with ARM instructions only (because some low level stuff
>> requires ARM mode): CPU_FLAGS without -mthumb.  The rest of the BSP will use
>> THUMB instructions: CPU_FLAGS with -mthumb.
> 
> That's your bug. Arm and thumb are different architectures, which must 
> not be mixed.

This is definitely not a bug.  The exception processing for example starts in
ARM mode.  It is also possible to mix THUMB and ARM functions.  This is called
interworking.  If you need position independent code you have to use ARM.

-- 
Sebastian Huber, Embedded Brains GmbH

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