vexpress and 11.08

Pawel Moll pawel.moll at arm.com
Mon Sep 26 13:28:57 UTC 2011


> I've heard that due to bugs all high bandwidth devices are flakey.

They are getting better and better though :-)

> Specifically, MMC and SATA media are unreliable and the best solution is
> to try USB.

With the latest official firmware (and IO FPGA) from the VE CD 3.0:

https://silver.arm.com/browse/VE030

MMC with the default card clock of ~500kHz is rock-solid :-) Personally
I actually use it with mmci.fmax=12000000, which makes it rather fast.
The downside is that I can't use any USB devices at the same time (well,
you can do some tricks with IRQ core affinity to make it work). So
6000000 (6MHz) is a safe compromise.

> I have just copied my 11.08 image to MMC and tried booting off that. I
> found that it does seem to hang but after 5 minutes or so it eventually
> gets to the command prompt. Once booted, using ssh to copy a large file
> gave a transfer rate of about 30kB/s.

With the increased MMC card clock it becomes really usable, but then you
may face an issue with the Ethernet ;-)

https://bugs.launchpad.net/linux-linaro/+bug/673820

Which can be fixed with even newer IO FPGA files, as mentioned in the
bug log.

Cheers!

Paweł





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