Hi Christophe,

Thanks for trying to clean up this tangled mess.

Christophe Leroy <[email protected]> writes:
> The only 64-bit Book3E CPUs we support is the e500mc.

AFAIK the e500mc is 32-bit?

We support e5500 and e6500 which are 64-bit Book3E.

They're derivatives of the e500mc AIUI.

So CONFIG_PPC_E500MC actually means e500mc *and later derivatives*.

You can see that with eg:

config SPE_POSSIBLE
        def_bool y
        depends on E500 && !PPC_E500MC

Because e500mc dropped SPE, and so therefore e5500 and e6500 don't have
it either.

And eg:

#ifdef CONFIG_PPC_E500MC
_GLOBAL(__setup_cpu_e6500)
        mflr    r6


> However our Kconfig allows configurating a kernel that has 64-bit
> Book3E support, but no e500mc support enabled. Such a kernel
> would never boot, it doesn't know about any CPUs.

That is true.

> To fix this, force e500mc to be selected whenever we are
> building a 64-bit Book3E kernel.

I think that's a reasonable fix, just it's important to differentiate
between CONFIG_PPC_E500MC (the symbol) and e500mc (the CPU).

> And add a test to detect futur situations where cpu_specs is empty.
                           future
>
> Signed-off-by: Christophe Leroy <[email protected]>
> ---
>  arch/powerpc/kernel/cputable.c         | 2 ++
>  arch/powerpc/platforms/Kconfig.cputype | 2 ++
>  2 files changed, 4 insertions(+)
>
..
> diff --git a/arch/powerpc/platforms/Kconfig.cputype 
> b/arch/powerpc/platforms/Kconfig.cputype
> index 5185d942b455..19fd95a06352 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -108,6 +108,8 @@ config PPC_BOOK3S_64
>  config PPC_BOOK3E_64
>       bool "Embedded processors"
>       select PPC_FSL_BOOK3E
> +     select E500
> +     select PPC_E500MC
>       select PPC_FPU # Make it a choice ?
>       select PPC_SMP_MUXED_IPI
>       select PPC_DOORBELL

I think that makes the select of PPC_E500MC below redundant:

config PPC_QEMU_E500
        bool "QEMU generic e500 platform"
        select DEFAULT_UIMAGE
        select E500
        select PPC_E500MC if PPC64


cheers

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