From: Segher Boessenkool <segher@kernel•crashing.org>
To: Michael Ellerman <mpe@ellerman•id.au>
Cc: Matt Brown <matthew.brown.dev@gmail•com>, linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH v2] powerpc/powernv: Use darn instr for random_seed on p9
Date: Tue, 1 Aug 2017 07:57:36 -0500 [thread overview]
Message-ID: <20170801125735.GJ13471@gate.crashing.org> (raw)
In-Reply-To: <87lgn555vs.fsf@concordia.ellerman.id.au>
On Mon, Jul 31, 2017 at 07:10:15PM +1000, Michael Ellerman wrote:
> And ___PPC_RA() is not quite right. The L field is only 2 bits wide, not
> the 5 that ___PPC_RA() allows.
>
> We don't have a __PPC_L() macro, because L fields vary in size and
> location. So I think you're best of open coding it, eg:
>
> +#define PPC_DARN(t, l) stringify_in_c(.long PPC_INST_DARN | \
> + __PPC_RT(t) | \
> + (((l) & 0x3) << 16))
It would be better if you could do a compile-time error if the L value
is out of range. Hrm, nothing else does such checking either?
Segher
next prev parent reply other threads:[~2017-08-01 13:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-07 7:02 [PATCH v2] powerpc/powernv: Use darn instr for random_seed on p9 Matt Brown
2017-07-11 9:34 ` Daniel Axtens
2017-07-13 0:47 ` Matt Brown
2017-07-13 2:44 ` Michael Ellerman
2017-07-31 9:10 ` Michael Ellerman
2017-08-01 12:57 ` Segher Boessenkool [this message]
2017-08-04 1:10 ` Matt Brown
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