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Date: Tue, 23 Jun 2009 11:28:23 +0530
Message-ID: <366f00c80906222258l2c577b4eq7c97d0430f7f7104@mail.gmail.com>
Subject: Re: Rootfs in eMMC: Kernel panic ...Attempted to kill init!
From: Sudeep K N <sudeepholla.maillist@gmail.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>,
       linux-arm-kernel@lists.arm.linux.org.uk, drzeus-mmc@drzeus.cx,
       linux-kernel@vger.kernel.org
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> Could you or Sudeep clarify whether the driver uses DMA or PIO?
>
I have option to use both. I tried you patch(rather hack) for PIO mode i.e
(flush_dcache_page called in the VFS layer). This solves the crash in polling
mode. I need to work for proper way of flushing in the MMC driver.
I am yet to try with DMA as I am not much familiar with the DMA driver and
need some time.

> 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.

Looks like the crash I am getting is similar to one you are explaining with
your experience with CF cards.


Thanks to both Catalin and Russell for making such a informative discussion on
ARM SMP and related cache know hows.

-- 
Regards,
Sudeep
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