Re: [PATCH] powerpc: Kconfig.cputype: Disallow TUNE_CELL on LE systems

On 21/09/15 09:18, Michael Ellerman wrote:

On Fri, 2015-09-18 at 16:17 +0200, Thomas Huth wrote:

quoted

It looks somewhat weird that you can enable TUNE_CELL on little
endian systems, so let's disable this option with CPU_LITTLE_ENDIAN.

Signed-off-by: Thomas Huth <redacted>
---
 I first thought that it might be better to make this option depend
 on PPC_CELL instead ... but I guess it's a bad idea to depend a
 CPU option on a platform option? Alternatively, would it make
 sense to make it depend on (GENERIC_CPU || CELL_CPU) instead?

Hmm, it's a little backward, but I think it would be fine, and less confusing
for users. Both PS3 and Cell select PPC_CELL, so it would work in both those
cases.

It's just that when you step through the kernel config (e.g. with "make
menuconfig"), you normally step through the "Processor support" first,
and then later do the "Platform support". I think most users won't look
back into "Processor support" again once they already reached the
"Platform support" section, so this TUNE_CELL option then might appear
unnoticed when you enable a Cell platform under "Platform support".

That's why thought that CPU_LITTLE_ENDIAN or (GENERIC_CPU || CELL_CPU)
might be the better option here... but if you think PPC_CELL is the
better way to go, I'm also fine to change my patch to use this instead
(in the end, TUNE_CELL is likely hardly used anymore nowadays, so it
should not be that bad if it does not appear "immediately" to the user).

 Thomas