>>datas are not correctly read by the chip, so I beleive this is because
>>virt_to_bus doesn't work with vmalloc addresses, am I wrong ?
>
>That's true, it doesn't. To get the physical address you need to walk
>pagetables as someone (either Roger or Ralf I think) pointed out. I think
>there is code in ptrace.c that shows how this is done but it's not really
>recommended practice.
>
>So, maybe the vmalloc idea wasn't such a good one after all and some
>completely new routine is needed.
OK. However, I need to find a temporary solution before someone
implements this new mecanism (I don't think I can do it with my current
knowledge of Linux mm). I would prefer avoiding walking the page tables,
this is complex and I've seen all Linus promises of quick death to
whoever would try to do that ;-)
What happens if I simply try to create an additional mapping for an
existing page ? Basically, what happens if I use ioremap on the physical
location of a kmalloc'ed page ?
Of course, I will end up having two virtual mappings to the same page,
but if I make sure to only actually use the uncachable one, will there be
a problem ? Would something prevent ioremap from creating a mapping for a
physical page in the SDRAM range ?
Regards,
Benjamin.
--
Perso. e-mail: <mailto:bh40@calva.net>
Work e-mail: <mailto:benh@mipsys.com>
BenH. Web : <http://calvaweb.calvacom.fr/bh40/>
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