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Bug#658759: disable l2 cache on kirkwood devices (workaround #658904)

On Mon, 2012-09-10 at 23:09 -0700, Jonathan Nieder wrote:
> Hi Ian,
> On Aug 30, 2012, Ian Campbell wrote:
> > I've just tried injecting the following onto the head of the zImage (in
> > a similar manner to flash-kernel's set_machine_id function):
> [...]
> > This works around the issue on my dreamplug (this is effectively the
> > same code sequence as what the u-boot fix does).
> >
> > I can see two ways of distributing this fix. Either a kernel patch gated
> > on CONFIG_ARCH_KIRKWOOD to some early bit of code or use devio in
> > flash-kernel + the installer build.
> Sorry I missed this before.  That sounds like an excellent idea for a
> kernel patch.  A kind user on the linux-arm-kernel@ list[1] recently
> mentioned he'd be willing to test patches, if you need a guinea pig,
> and I assume once a patch is written and tested it should be possible
> to get useful feedback from the list.

My main concern with doing this on the kernel side is that it will
eventually fall foul of the attempts to reduce everything to a single
kernel image, since the code will necessarily be quite kirkwood specific
and run very early on.

Martin's testing of di on ARM[0] suggests this issue isn't all that
widespread, which lead me to conclude that the risk of making a change
like this (either in the kernel or the installer/flash-kernel) for
Wheezy was not worth the chance of breaking some other kirkwood device.


[0] https://lists.debian.org/debian-boot/2012/09/msg00052.html

Ian Campbell
Current Noise: Crowbar - To Build A Mountain

Sex is like air.  It's only a big deal if you can't get any.

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