On 11.02.2013 20:19, Conor O'Gorman wrote:
On Mon, 2013-02-11 at 17:50 +0100, Matti Laakso wrote:
This patch disables the execute-in-place (XIP) support for flash on
lantiq. This has to be disabled since the bus which flash is connected
to does not support unaligned accesses. Resolves data bus errors on
Lantiq routers with Intel command set flash.
Interesting, but does lead to a couple of questions.
I would have expected instruction fetches to be well aligned?
And secondly what sort of code are you running directly from flash?
Thanks,
Conor
The problem is that XIP is (ab)used by jffs2, among others, to do reads with plain memcpy
directly from flash. As far as I understand, memcpy on MIPS is allowed to do unaligned
accesses but the underlying bus doesn't support it, so problems occur. "Proper"
XIP should work, isn't that how U-Boot stored in flash, for example, works?
Best regards,
Matti
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