From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Date: Tue, 21 Sep 2010 23:19:50 +0000 Subject: Re: [PATCH] fbmem: Fix fb_read, fb_write unaligned accesses. Message-Id: <20100921161950.b7f45273.akpm@linux-foundation.org> List-Id: References: <201009180123.48303.james@albanarts.com> In-Reply-To: <201009180123.48303.james@albanarts.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: James Hogan Cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, "David S. Miller" , Dave Airlie , Marcin Slusarz , Florian Tobias Schandinat , Denys Vlasenko , Jesse Barnes , James Simmons On Sat, 18 Sep 2010 01:23:47 +0100 James Hogan wrote: > Apologies for corrupted patch. I'll try again. > Comments? I'd also appreciate if somebody familiar with sbus on sparc > could check this patch is sane since I know virtually nothing about sbus > and am not in a position to compile for sparc, let alone test on it: > > fb_{read,write} access the framebuffer using lots of fb_{read,write}l's > but don't check that the file position is aligned which can cause > problems on some architectures which do not support unaligned accesses. What are these "problems"? I'd have thought they would be fairly fatal, in which case this is a high-priority patch. But I'd also have thought that the problems would have been noted before now. So I assume that you're doing something which nobody has done before. Confused. Help? > Since the operations are essentially memcpy_{from,to}io, new > fb_memcpy_{from,to}fb macros have been defined and these are used > instead. > > For Sparc, fb_{read,write} macros use sbus_{read,write}, so this defines > new sbus_memcpy_{from,to}io functions the same as memcpy_{from,to}io but > using sbus_{read,write}b instead of {read,write}b.