From mboxrd@z Thu Jan 1 00:00:00 1970 From: Albert ARIBAUD Date: Tue, 15 Oct 2013 19:07:49 +0200 Subject: [U-Boot] [PATCH] disk:efi: avoid unaligned access on efi partition In-Reply-To: References: <1381498270-24342-1-git-send-email-p.wilczek@samsung.com> <000601cec8b7$ae803050$0b8090f0$%wilczek@samsung.com> <20131014134626.7e691591@lilith> <20131014150002.2b1cfe82@lilith> <20131014154811.2852096b@lilith> <20131014171817.56ec25b6@lilith> <20131014192605.6793e405@lilith> <20131015182148.47c3af4e@lilith> Message-ID: <20131015190749.53df21c6@lilith> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi M?ns, On Tue, 15 Oct 2013 17:29:24 +0100, M?ns Rullg?rd wrote: > Albert ARIBAUD writes: > > > Hi M?ns, > > > > On Tue, 15 Oct 2013 16:23:44 +0100, M?ns Rullg?rd > > wrote: > > > >> On the compiler side, gcc traditionally did not issue unaligned > >> load/store instructions on ARM. > > > > Please be specific: gcc did not emit *native* unaligned accesses. > > Please explain what you mean by "native unaligned access". By this I mean an unaligned access performed with a single transfer, initiated by a single processor instruction, as opposed to an unaligned access performed with a series of smaller, aligned, transfers (and possibly additional operations) initiated by a sequence of processor instructions (emulated, if you will). Prior to 4.7, gcc did emit unaligned accesses if instructed to at the source code level; they were however emulated. From 4.7 onward, it was possible to choose whether unaligned transfers should be performed native or emulated, the default being native for ARMv6+, and emulated for the rest. Amicalement, -- Albert.