> -----Original Message----- > From: glik...@secretlab.ca [mailto:glik...@secretlab.ca] On > Behalf Of Grant Likely > Sent: Thursday, July 08, 2010 12:38 AM > To: Benjamin Herrenschmidt > Cc: Steve Deiters; linuxppc-dev@lists.ozlabs.org > Subject: Re: [PATCH] arch/powerpc/lib/copy_32.S: Use > alternate memcpy for MPC512x and MPC52xx > > On Wed, Jul 7, 2010 at 11:10 PM, Benjamin Herrenschmidt > <b...@kernel.crashing.org> wrote: > > On Tue, 2010-06-29 at 11:04 -0500, Steve Deiters wrote: > >> These processors will corrupt data if accessing the local bus with > >> unaligned addresses. This version fixes the typical case > of copying > >> from Flash on the local bus by keeping the source address always > >> aligned. > > > > Shouldn't this be solved by using memcpy_to/fromio ? > > Maybe. plain memcpy() access to anything localbus-attached > on the mpc5xxx is the wrong thing to do. memcpy_to/fromio > might do the right thing; but the caller must understand the > limitations of the localplus bus. The byte-wise alignment > that memcpy_to/fromio() does may not work (depending on > configuration). > > Steve, what code is doing a memcpy from flash? > > g.
This was done in the JFFS2 code, in fs/jffs2/scan.c. At least in one function, in jffs2_scan_dirent_node it was using memcpy on a localbus mapped structure. I was getting JFFS2 filesystem corruption because of this. In fact I first tried changing this to memcpy_fromio and it fixed that particular problem. I was concerned though that other places I was not aware of might be using memcpy from the localbus in a similar manner so I decided to just tweak the memcpy routine. Just out of curiousity, what configuration might cause a byte-wise alignment not to work? _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
