Re: [uClinux-dev] [PATCH v2 1/6] m68k: merge mmu and non-mmu versions of muldi3

Greg Ungerer
2011-04-20T09:32:09Z

On 20/04/11 19:12, Philippe De Muyter wrote:
> On Wed, Apr 20, 2011 at 10:55:15AM +0200, Geert Uytterhoeven wrote:
>> On Wed, Apr 20, 2011 at 10:06, Sam Ravnborg<sam@ravnborg.org> wrote:
>>> Hi Greg.
>>>
>>>> +
>>>> +#if defined(__mc68020__) || defined(__mc68030__) || \
>>>> + Ã¡ Ã¡defined(__mc68040__) || defined(__mc68060__)
>>>
>>> Why use these to decide if this is MMU or not?
>>> This code is not exposed to user-space so we can rely on CONFIG_* symbols.
>>> IMO the CONIFG_* symbols is easier to read/maintain.
>>
>> Because technically it doesn't depend on having a MMU or not, but on having
>> the full 32-bit multiplication instruction or not.
>>
>> Does Coldfire-with-MMU (for which we haven't integrated the support
>> yet) have that
>> instruction?
>
> Actually, MCF547x& MCF548x (CFv4e family) are integrated but without their
> limited MMU functionality.
>
> freescale had even written an mmu port for 2.6.25 but has not pushed it
> upstream. This port can be found on their site or in the openwrt repository.

Part of my plan with the merge of m68k and m68knommu is to make
it easy to support the v4e parts with MMU enabled. And certainly as
I work through cleaning the individual files up I am doing it
with this in mind. Of course most of the code to support the v4e
is the same no matter if you have the MMU enabled or not.

I have Freescales 2.6.25 kernel, but it is really only a reference
point for this work.

> MCF547x& MCF548x do not have that instruction.

Thats right. I believe the processors listed in the patch are
the only ones that currently support the 64bit mul.

Regards
Greg

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Greg Ungerer -- Principal Engineer EMAIL: gerg@snapgear.com
SnapGear Group, McAfee PHONE: +61 7 3435 2888
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