Re: [PATCH 14/15] mips: panic if vector register partitioning is implemented

[David Daney <ddaney.cavm@gmail.com>]

On 01/27/2014 07:23 AM, Paul Burton wrote:
> No current systems implementing MSA include support for vector register
> partitioning which makes it somewhat difficult to implement support for
> it in the kernel. Thus for the moment the kernel includes no such
> support. However if the kernel were to be run on a system which
> implemented register partitioning then it would not function correctly,
> mishandling MSA disabled exceptions. Calling panic when run on a system
> with vector register partitioning implemented ensures that we're not
> caught out by this later but instead reminded to implement support once
> such a system is available.
>
> Signed-off-by: Paul Burton <paul.burton@imgtec.com>
> ---
>   arch/mips/kernel/cpu-probe.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
> index 852e085..003ba3c 100644
> --- a/arch/mips/kernel/cpu-probe.c
> +++ b/arch/mips/kernel/cpu-probe.c
> @@ -1193,9 +1193,13 @@ void cpu_probe(void)
>   	else
>   		c->srsets = 1;
>
> -	if (cpu_has_msa)
> +	if (cpu_has_msa) {
>   		c->msa_id = cpu_get_msa_id();
>
> +		if (c->msa_id & MSA_IR_WRPF)
> +			panic("Vector register partitioning unimplemented!");

You should probably use a WARN_ON() instead.  There is no reason to 
crash the kernel for this condition is there?

> +	}
> +
>   	cpu_probe_vmbits(c);
>
>   #ifdef CONFIG_64BIT
>