jffs2 and unaligned access

Segher Boessenkool segher at kernel.crashing.org
Thu May 8 06:42:28 EST 2008

>> memcpy_from/to_io() use word aligned accesses on the io side of 
>> memory.
>> The MPC5200 local plus bus where our flashes are connected does not
>> allow unaligned accesses, so we have to use the io versions of memcpy.
> But this region of flash is marked as suitable for execute-in-place,
> otherwise the point() function wouldn't be working to give a direct
> pointer to it. It sounds like we shouldn't be allowing that.
> Which in turn means that perhaps we should have a property in the
> corresponding node in the device-tree which indicates that it's not
> suitable for direct access?

This isn't usually a property of the flash device, but of the various
buses/controllers above the flash device.  The device tree should mimic
reality (and it does, it just seems the kernel doesn't use this 


More information about the Linuxppc-dev mailing list