Re: [v3 PATCH 8/8] RISC-V: Assign hwcap only according to boot cpu.

[Christoph Hellwig]

> +      * We don't support running Linux on hertergenous ISA systems.
> +      * But first "okay" processor might not be the boot cpu.
> +      * Check the ISA of boot cpu.

Please use up your available 80 characters per line in comments.

> +             /*
> +              * All "okay" hart should have same isa. We don't know how to
> +              * handle if they don't. Throw a warning for now.
> +              */
> +             if (elf_hwcap && temp_hwcap != elf_hwcap)
> +                     pr_warn("isa mismatch: 0x%lx != 0x%lx\n",
> +                             elf_hwcap, temp_hwcap);
> +
> +             if (hartid == boot_cpu_hartid)
> +                     boot_hwcap = temp_hwcap;
> +             elf_hwcap = temp_hwcap;

So we always set elf_hwcap to the capabilities of the previous cpu.

> +             temp_hwcap = 0;

I think tmp_hwcap should be declared and initialized inside the outer loop
instead having to manually reset it like this.

> +     }
>  
> +     elf_hwcap = boot_hwcap;

And then reset it here to the boot cpu.

Shoudn't we only report the features supported by all cores?  Otherwise
we'll still have problems if the boot cpu supports a feature, but not
others.

Something like:

        for () {
                unsigned long this_hwcap = 0;

                for (i = 0; i < strlen(isa); i++)
                        this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];

                if (elf_hwcap)
                        elf_hwcap &= this_hwcap;
                else
                        elf_hwcap = this_hwcap;
        }