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Re: [PATCH V2 8/8] MIPS: BMIPS: Add SMP support code for BMIPS43xx/BMIPS

To: Florian Fainelli <ffainelli@freebox.fr>, Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH V2 8/8] MIPS: BMIPS: Add SMP support code for BMIPS43xx/BMIPS5000
From: Kevin Cernekee <cernekee@gmail.com>
Date: Sat, 12 Nov 2011 08:07:22 -0800
Cc: linux-mips@linux-mips.org
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On Sat, Nov 12, 2011 at 6:31 AM, Florian Fainelli <ffainelli@freebox.fr> wrote:
> - considering that BMIPS4350 has a shared TLB, is it still working fine? I 
> must
> say that I have not yet tested on e.g: BCM6358

BCM6368 (which I did test) has a private TLB for each thread.  I have
not tested any of the shared TLB chips.

It is possible that more work will be required to cover the shared TLB case.

> - there a couple of places in the code where we have:
>
> #if defined (CONFIG_BMIPS_4350) || defined (CONFIG_BMIPS_4380)
>  ... do something
> #elif defined(CONFIG_BMIPS_4380)
>
> can we turn this into a #if BMIPS43xx case .. #endif  #if BMIPS5000 ... #endif
> to allow a single image supporting both BMIPS43xx and BMIPS5000?

Although it would be easy to check current_cpu_type() for the cases in
smp-bmips.c, there are other decisions (not in this patchset) that are
harder to make at runtime.  One obvious case is
cpu-feature-overrides.h; other cases include low-level code sequences
in the exception vectors, power management standby/resume/reentry
assembly code, HIGHMEM and cache configuration, memory map, etc.

Side note: one of Ralf's earlier comments on this patch was a request
to use pr_info() instead of printk().  This somehow fell off my TODO
list.  I will fix it and submit V4 later today.

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