[ECOS] Big Endian on ARM

[ECOS] Big Endian on ARM

[Wilson Kwan]

Hi everyone,

I'm trying to build my eCos application in big endian mode and it seems as
though the arm-elf-gcc compiler is building it in little endian mode. I'm
using the Cirrus Logic 7211 board and I checked off "use big endian mode" in
the config tool. Should I add the -mbig-endian option to the global compiler
flags or is there a better place to do this?

Anyone else have experience with the Cirrus boards operating in big-endian
mode?

Thanks in advance,

Wilson Kwan

Re: [ECOS] Big Endian on ARM

[Jonathan Larmour]

Wilson Kwan wrote:
> 
> Hi everyone,
> 
> I'm trying to build my eCos application in big endian mode and it seems as
> though the arm-elf-gcc compiler is building it in little endian mode. I'm
> using the Cirrus Logic 7211 board and I checked off "use big endian mode" in
> the config tool. Should I add the -mbig-endian option to the global compiler
> flags or is there a better place to do this?

This is an infelicity of the configuration data. There should really be
something that disables the "use big endian mode" option when it's not
supported by the platform. It has no effect on the edb7xxx platform.

Jifl
-- 
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine

Re: [ECOS] Big Endian on ARM

[Wilson Kwan]

Thanks Jifl for the quick response.

The Cirrus documentation seems to indicate that the processor will operate
in big endian mode. What are the reasons for the platform not supporting
this mode?

Thanks again,

Wilson


Wilson Kwan wrote:
>
> Hi everyone,
>
> I'm trying to build my eCos application in big endian mode and it seems as
> though the arm-elf-gcc compiler is building it in little endian mode. I'm
> using the Cirrus Logic 7211 board and I checked off "use big endian mode"
in
> the config tool. Should I add the -mbig-endian option to the global
compiler
> flags or is there a better place to do this?

This is an infelicity of the configuration data. There should really be
something that disables the "use big endian mode" option when it's not
supported by the platform. It has no effect on the edb7xxx platform.

Jifl
--
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine

Re: [ECOS] Big Endian on ARM

[Jonathan Larmour]

Wilson Kwan wrote:
> 
> Thanks Jifl for the quick response.
> 
> The Cirrus documentation seems to indicate that the processor will operate
> in big endian mode. What are the reasons for the platform not supporting
> this mode?

No-one has done it :-). Actually the PID is the only ARM platform that
supports big-endian operation. If you want to see what is required to work
in big-endian, search for CYGHWR_HAL_ARM_BIGENDIAN in the PID HAL and make
the equivalent changes to the edb7xxx HAL.

And, of course, then contribute them back :-).

Jifl
-- 
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine