[PATCH] jffs2 summary allocation
David Brownell
david-b at pacbell.net
Fri Apr 4 19:58:38 EDT 2008
On Friday 04 April 2008, Josh Boyer wrote:
>
> > ... This means specifically that you may _not_ use the
> > memory/addresses returned from vmalloc() for DMA. ...
> >
> > So I'm rather surprised to see *ANY* kernel code trying to do
> > that. That rule has been in effect for many, many years now.
>
> I don't think it was intentional. You're going through several layers
> here:
>
> JFFS2 -> mtd parts -> mtd dataflash -> atmel_spi.
>
> Typically MTD drivers aren't doing DMAs to flash and JFFS2 has no idea
> which particular chip driver is being used because it's abstracted by
> MTD.
That's true ... although I can imagine using DMA to
avoid dcache trashing if its setup cost is low enough,
with either NAND or NOR chips.
Still: in this context vmalloc() is wrong.
- Dave
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