[RFC v3 PATCH 00/25] Allow NOMMU for MULTIPLATFORM

[Vladimir Murzin]

Hi,

On 12/12/16 07:07, mickael guene wrote:
> Hi all,
> 
>  You can find an R toolchain here:
> https://github.com/mickael-guene/fdpic_manifest/releases/download/v7-r-1.0.1/toolset-v7-r-1.0.1-0-gbdcc6a7c-armv7-r.tgz
> 
>  It's an fdpic toolset for cortex-r cpu class. gcc version is
> quite old (4.7).
> 
>  Note also that generated code may crash on class A cpu due to
> generation of udiv/sdiv which is optional for class A.
> (cortex a15 is ok but not a9).
> 
> Hope it helps

Unfortunately, it doesn't help because it depends on FDPIC Linux patches
which are out of tree and no link has been given.

M-class toolchain should just work with A-class; you don't even need to
disable MMU to try it out after d782e42 ("ARM: 8594/1: enable binfmt_flat on
systems with an MMU").

Cheers
Vladimir

> 
> Regards
> Mickael
> 
> On 12/11/2016 09:01 PM, Peter Korsgaard wrote:
>>>>>>> "Afzal" == Afzal Mohammed <afzal.mohd.ma at gmail.com> writes:
>>
>> Hi,
>>
>>  >> You can build a toolchain and initramfs with Buildroot. Have a look at
>>  >> the stm32f429 nommu config:
>>  >>
>>  >> https://git.buildroot.net/buildroot/tree/configs/stm32f429_disco_defconfig
>>
>>  > iiuc, it builds one for Cortex-M. i already had a file system w/
>>  > busybox compiled using a Cortex-M toolchain (stolen from
>>  > Pengutronix's OSELAS.Toolchain), which works on Cortex M4 (Vybrid
>>  > VF610 M4 core). But it does not work here, i.e. on Cortex A, seems the
>>  > above mentioned also would have the same effect.
>>
>> Hmm, I'm not sure why a cortex-M toolchain wouldn't work on cortex-A, I
>> thought the 'M' instruction set was a pure subset of the 'A'.
>>
>>  > And in buildroot, couldn't see Cortex R option in menuconfig, and
>>  > selecting Cortex-A's excludes flat binary target & presents only with
>>  > ELF.
>>
>> We indeed don't have cortex-R support. I'm not aware of any cortex-R
>> Linux support.
>>
>> When you select a cortex-A variant, then we enable MMU support by
>> default, but you can disable it under toolchain options (Enable MMU) and
>> then the flat binary option is available.
>>
>