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Re: Making use of the BigRamPlus?



On Tue, Dec 17, 2013 at 10:26 AM, Ingo Jürgensmann
<ij@2013.bluespice.org> wrote:
> On 2013-12-17 10:17, Geert Uytterhoeven wrote:
>> On Tue, Dec 17, 2013 at 10:13 AM, Ingo Jürgensmann
>> <ij@2013.bluespice.org> wrote:
>>>
>>> spice:/home/ij# modprobe phram phram=bigram,0x50000000,200Mi
>>> spice:/home/ij# mkswap /dev/mtd0
>>> mkswap: warning: truncating swap area to 17179869184 KiB
>
>> Strange... So it failed to write more data?
>> Can you dd 256 MiB to it?
>
> spice:/home/ij# dd if=/dev/zero of=/dev/mtd0 bs=1M
> dd: error writing '/dev/mtd0': No space left on device
> 257+0 records in
> 256+0 records out
> 268435456 bytes (268 MB) copied, 148.747 s, 1.8 MB/s

So it's working. No idea why mkswap failed early.

It may be a good idea to truncate a big file to 256 MiB, sha1sum it,
copy it to /dev/mtd0, and run sha1sum -c on /dev/mtd0 in a loop,
to rule out memory corruption.

> Not very speedy, eh? I would've expected around 10 MB/s...

Now replace the call to ioremap() in drivers/mtd/devices/phram.c by
ioremap_fullcache() to switch from maximum impulse to warp 9 ;-)

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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