Re: Rootfs in eMMC: Kernel panic ...Attempted to kill init!

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Mon, Jun 22, 2009 at 05:13:16PM +0100, Catalin Marinas wrote:
> Well, I get this kind of errors (with /sbin/init) every time I try ext2
> on CompactFlash (with pata_platform). You could try with USB as well on
> a RealView/EB+ARM11MPCore board.

Is USB now usable on the rev.B board I have?

> Could you or Sudeep clarify whether the driver uses DMA or PIO?

If I knew what this "eMMC" was...

> In my case (ext2 over pata_platform), there is no flush_dcache_page()
> call after the page was written with data from the CompactFlash (neither
> the driver nor the VFS layer do this and we used hardware tracing to
> double-check). When the page is mapped into user space,
> update_mmu_cache() is called but the page hasn't been marked as dirty
> and no D-cache flushing occurs. Calling flush_dcache_page() in
> mpage_end_io_read() works around this issue.

As already covered, there's no chance of adding such a call to the
generic kernel.  It's the responsibility of the drivers to ensure that
data they read in hits the underlying page - in the same way that DMA
does.