Re: [ECOS] arm-thumb advice needed

[Jonathan Larmour <jlarmour at redhat dot com>]

Cristian VLASIN wrote:
> 
>                 Hi all,
> 
>         I'm trying to compile my eCos with thumb and I think something is wrong
> because my binary gets bigger than the non-thumb one.
>         Here is what I have done:
>                 -built the binutils as described for thumb on eCos webpage
> http://sources.redhat.com/ecos/tools/linux-thumb-elf.html  (it seems to me
> that the page is similar with the simple arm one - should it be so?)
>                 -built gcc (3.0.3) also as described there
>                 -copied an example of redboot (which I have previously compiled for my
> EB40 card)
>                 -adjusted compiler flags with "-mthumb-interworking" and activated
> thumb+interworking in HAL (it doesn't compile with simple "-mthumb")
>                 -compiled and obtained a binary which is larger than the first one
> 
>         Can anyone tell me if I'm right or give me some advice to make it right?

No, -mthumb is what you need, and explains why you're seeing larger
binaries - they are still ARM mode executables, but with extra bits in to
allow it to link with thumb code.

At a guess it doesn't compile because you haven't built your GCC with a
thumb multilib, resulting in errors when linking with libgcc. If so you
need to edit gcc/config/arm/t-arm-elf and rebuild gcc.

Jifl
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