Messages in this thread |  | | Date | Fri, 16 Dec 2022 13:15:43 -0600 | From | Segher Boessenkool <> | Subject | Re: [PATCH v1] powerpc/64: Set default CPU in Kconfig |
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Hi!
On Thu, Dec 15, 2022 at 09:42:02PM +0100, Pali Rohár wrote: > On Wednesday 07 December 2022 14:38:40 Christophe Leroy wrote: > > default "power8" if POWER8_CPU > > default "power9" if POWER9_CPU > > default "power10" if POWER10_CPU > > + default "e500mc64" if E5500_CPU > > Now I'm looking at this change again... and should not E5500_CPU rather > enforce -mcpu=e5500 flag? I know that your patch moves e500mc64 flag > from the Makefile to Kconfig, but maybe it could be changed in some > other followup patch... > > Anyway, do you know what is e500mc64 core? I was trying to find some > information about it, but it looks like some unreleased freescale core > which predates e5500 core.
It looks that way yes. It was submitted at <https://gcc.gnu.org/pipermail/gcc-patches/2009-November/273251.html> and committed as <https://gcc.gnu.org/g:b17f98b1c541>. It looks as if it was based on the e500mc core, while e5500 is a new core (or significantly different anyway).
> ISA (without extensions like altivec) seems > to be same for e500mc64, e5500 and e6500 cores and difference is only > pipeline definitions in gcc config files. So if my understanding is > correct then kernel binary compiled with any of these -mcpu= flag should > work on any of those cores. Just for mismatches core binary will not be > optimized for speed.
It appears the E500MC64 never made it outside of FSL, so it is best not to use it at all, imo.
Segher
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