Messages in this thread | | | From | Arnd Bergmann <> | Date | Fri, 8 Jul 2022 22:04:08 +0200 | Subject | Re: [PATCH] powerpc: e500: Fix compilation with gcc e500 compiler |
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On Fri, Jul 8, 2022 at 7:12 PM Pali Rohár <pali@kernel.org> wrote: > > On Monday 04 July 2022 14:07:10 Arnd Bergmann wrote: > > Another problem I see is that a kernel that is built for both E500 and E500MC > > uses -mcpu=e500mc and may not actually work on the older ones either > > (even with your patch). > > Such configuration is not supported, see arch/powerpc/platforms/Kconfig.cputype: > > config PPC_E500MC > bool "e500mc Support" > select PPC_FPU > select COMMON_CLK > depends on E500 > help > This must be enabled for running on e500mc (and derivatives > such as e5500/e6500), and must be disabled for running on > e500v1 or e500v2. > > Based on this option you can enable either support for e500v1/e500v2 or > for e500mc. But not both.
This looks like a bad decision in Kconfig though, as there is nothing enforcing the rule: If you want support for E500MC, you have to select PPC_85xx, which implies E500 and allows selecting any combination of E500v1, E500v2 and E500MC based machines, but enabling any E500MC based one breaks all the others.
If this is a hard dependency, I think it should be enforced by making E500MC a separate top-level option in the "Processor Type" choice statement. However, if they can actually coexist, the help text and the Makefile need to be fixed.
Arnd
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