Re: [PATCH] powerpc: Make set_endian() return EINVAL when not supporting little endian

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 26/08/2021 à 05:41, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>> There is no point in modifying MSR_LE bit on CPUs not supporting
>> little endian.
> 
> Isn't that an ABI break?

Or an ABI fix ? I don't know.

My first thought was that all other 32 bits architectures were returning -EINVAL, but looking at the 
man page of prctl, it is explicit that this is powerpc only.

> 
> set_endian(PR_ENDIAN_BIG) should work on a big endian CPU, even if it
> does nothing useful.

Fair enough. But shouldn't in that case get_endian() return PR_ENDIAN_BIG instead of returning EINVAL ?

We can do one or the other, but I think it should at least be consistant between them, shouldn't it ?

Christophe