Re: [arm-gnu] thumb code calling arm subroutine causes undefined insn exception

[42Bastian <list-bastian.schick@xxxxxxxxxxx>]

Am 28.04.2010 16:02, schrieb Andrew Kohlsmith (mailing lists account):
> On Sunday 25 April 2010 10:43:51 pm Mark Mitchell wrote:
>> Andrew Kohlsmith (mailing lists account) wrote:
>>> Since I am already using -mcpu=arm7tdmi, would this indicate that there
>>> is a bug in the compiler wherein it is assuming that the BLX instruction
>>> exists on the ARM7TDMI/TDMI-S?
>>
>> Please post your exact options for all of (a) code compiled with
>> GCC/G++, (b) code assembled with GAS, (c) link line.
>
> Actually some further inspection seems to lead to the conclusion that
> incorrect bootup code (in my case it's using msr in thumb mode) causes the
> linker to become confused.
>
> -A.
>
> boot.s:
> ------------------
> .equ MIN_STACK,         0x0004          /* enough for a RET */
> .equ IRQ_STACK_LEN,     0x0080          /* 128 words */
> .equ STACK_LEN,         0x0200          /* 512 words */
>
> /* .text is used instead of .section .text so it works with arm-aout too. */
>
>         .text
>         .code 32
>
>         .align  0
>
>         .extern main
>         .global start
>         .global endless_loop
>
> start:
>         ldr r0, =thumb_start + 1                /* +1 to set LSB to
identify
> destination as thumb code */
>         bx r0

>
>         .code 16

You should add
	.thumb_func
and then omit the above +1

>
> thumb_start:


-- 
42Bastian
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