Re: Hit BUG_ON in dma-mapping.c:425 (RFC)

Artem Bityutskiy
2011-03-24T11:08:07Z

On Thu, 2011-03-24 at 09:27 +0000, Russell King - ARM Linux wrote:
> The only real answer I can give is: if you want to deal with DMA, you
> absolutely must conform to the restrictions on DMA which means that you
> can't pass vmalloc addresses to the DMA API.

I see, thanks. Well, I do not see any issues with changing MTD-related
SW (JFFS2, UBI, UBIFS, etc) to use kmalloc. But this would require som
non-trivial efforts, although I believe this is doable.

Basically, we have to work with entire eraseblocks often, which may be
128KiB or 256KiB or even 512KiB nowadays. And we vmalloc the
eraseblock-sized buffers in these cases.

We could instead work with arrays of pages (or multiple pages), and then
do things like readv/writev. But this requires a brave knight who'd come
and just implemented this, or a company who'd fund someone to work on
this.

--
Best Regards,
Artem Bityutskiy (Артём Битюцкий)