From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Date: Tue, 5 Jan 2010 13:59:27 -0600 Subject: [U-Boot] io.h In-Reply-To: References: Message-ID: <20100105195927.GA26296@loki.buserror.net> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Sat, Dec 19, 2009 at 11:40:40AM +0330, seyyed morteza havaedgi wrote: > I working on mpc8272. in the file io.h there is "twi 0,RA,0" instruction. > what this instruction means and what it does? In accordance with powerpc programmers manual this instruction must do nothing because the TO field is zero. It turns a data dependency on RA into a flow control dependency (even though the decision always ends up being not to trap), which can then be ordered by a following isync. -Scott