Re: memcpy_fromio in dmi_scan.c

From: Robin Holt
Date: Thu Apr 25 2013 - 06:02:52 EST

On Wed, Apr 24, 2013 at 09:22:08PM +0200, Jean Delvare wrote:
> Hi Tony,
> Thanks for stepping in.
> Le Tuesday 23 April 2013 à 22:00 +0000, Luck, Tony a écrit :
> > > I don't have much knowledge about IA64 either. All I see is that while
> > > x86 implements memcpy_fromio() with memcpy [1], ia64 implements it with
> > > readb [2]. There must be a reason for that, and I can only suppose that
> > > memcpy on __iomem pointers doesn't work on IA64. If memcpy doesn't work
> > > then I can't see memcmp working.
> >
> > On most platforms readb() just ends up doing a regular dereference of the
> > address ... so I'd expect that memcmp would work just fine. The exception
> > is the old SGI sn2 which end up calling ___sn_readb() ... which does something
> > weird with sn_dma_flush() after doing the dereference of *addr. I don't

sn_dma_flush has a good description at the beginning of it. It is only
related to activity on PCI attached devices and a memcmp should be fine.
It must be that our prom produces a bad DMI table.

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