Messages in this thread | | | Subject | Re: [PATCH] jffs2 summary allocation | From | Josh Boyer <> | Date | Fri, 04 Apr 2008 18:21:22 -0500 |
| |
On Fri, 2008-04-04 at 16:09 -0700, David Brownell wrote: > On Friday 04 April 2008, Andrew Morton wrote: > > > I'm assuming from the trace that the arm code tried to put that memory > > under DMA (or at least, passed it into part of the DMA management code to > > get the various caches sorted out) and that the arm DMA support code > > doesn't like being given vmalloced memory. > > Actually, Documentation/DMA-Mapping.txt has a section right up > front called "What memory is DMA'able?" ... which despite its > ungrammatical title, says clearly: > > ... 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.
josh
| |