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Re: [PATCH] Use a sensible tlbex default for unknown CPUs

To: Thiemo Seufer <ths@networkno.de>
Subject: Re: [PATCH] Use a sensible tlbex default for unknown CPUs
From: "Maciej W. Rozycki" <macro@linux-mips.org>
Date: Thu, 25 Oct 2007 18:08:04 +0100 (BST)
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org
In-reply-to: <20071025155912.GD3994@networkno.de>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20071025155912.GD3994@networkno.de>
Sender: linux-mips-bounce@linux-mips.org
On Thu, 25 Oct 2007, Thiemo Seufer wrote:

> currently the kernel panics when it boots on an unknown CPU model
> (with an unknown PRID). Based on the assumption that the majority
> of newly supported CPU will conform to Release 2 standard, I wrote
> the appended patch which handles unknown CPUs as R2. It isn't
> completely bulletproof, as (yet unsupported) non-R1/R2 CPUs may
> use the AT config bits for different purposes. I still think this
> is good enough a test.

 Good idea in general, but do we have to rely on the undefined?  How 
about this:

> +             /* Panic if this isn't a Release 2 CPU. */
> +             if (!((read_c0_config() & MIPS_CONF_AT) >> 13)) {

        if (!(current_cpu_data.isa_level &
              (MIPS_CPU_ISA_M64R2 | MIPS_CPU_ISA_M32R2))) {

instead for example?

  Maciej

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