Re: Making use of the BigRamPlus?
Hi Ingo,
On Mon, Dec 16, 2013 at 3:14 PM, Ingo Jürgensmann <ij@2013.bluespice.org> wrote:
> On 2013-12-16 14:41, Geert Uytterhoeven wrote:
>> On Mon, Dec 16, 2013 at 11:57 AM, Ingo Jürgensmann
>
>>>> BigRamplus is Z3, not Z2, so it won't show up.
>>>
>>> Uhm... is there any reason why this is limited to Z2?
>>
>> Because it's called z2ram?
>> So far, no one played with Z3 RAM boards.
>
> So far I thought of Z3 being a superset of Z2 and assumed Z3 Ram should be
> recognized as Z2 Ram, although it might be rather slow when accessed as Z2.
But you can't access Z3 address spaces through Z2.
>>>> You can try CONFIG_MTD_PHRAM to create a block device and use it as
>>>> sawp.
>>>
>>> But with that I would need to define the memory in memfile, I guess, but
>>> then again it gets ignored when it's not in the proper order, because I
>>> want
>>> the kernel to get loaded into Fastmem (it doesn't work with the
>>> BigRamPlus
>>> yet anyway).
>>
>> No, don't put in in the memfile. I haven't looked at the code yet, but I
>> expect
>> the driver to ioremap() the RAM based on a kernel command line parameter.
>> We could add code to detect it automatically it if the above works.
>
> Ok, built a new kernel with MTD support built in (i.e. not as module). Have
Modular phram might be easier for experimenting, though.
The top of drivers/mtd/devices/phram.c has:
* Usage:
*
* one commend line parameter per device, each in the form:
* phram=<name>,<start>,<len>
* <name> may be up to 63 characters.
* <start> and <len> can be octal, decimal or hexadecimal. If followed
* by "ki", "Mi" or "Gi", the numbers will be interpreted as kilo, mega or
* gigabytes.
*
* Example:
* phram=swap,64Mi,128Mi phram=test,900Mi,1Mi
> to try it later whether this works... are there any user land tools needed?
I don't think you need any special userland tools. You should see a new
block device, and run mkswap and swapon on it.
To measure performance, you can use e.g. dd, or hdparm (which will
compare to buffer cache in system RAM).
Good luck!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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