From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Date: Mon, 8 Aug 2011 15:42:38 -0500 Subject: [U-Boot] problem with mpc837x start.S In-Reply-To: References: , , <20110801134822.36780bd4@schlenkerla.am.freescale.net>, , <20110802102109.6909e3da@schlenkerla.am.freescale.net>, , <20110803104839.56ef4383@schlenkerla.am.freescale.net> Message-ID: <4E404A3E.8060006@freescale.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 08/04/2011 06:37 AM, shawn Bai wrote: > When enlarging Nor Flash to 4GiB, the AM in OR0 is 0x0000_0, where the number of zero is 17. > > According to what is said in datasheet, if the bit value of some bit in address mask is 0, > then the corresponding bit in address will be masked. > > So, the higher 17 bits in address will be masked, is it right ? > > If so, the range accessed in flash is just 32KBytes from the BA in BR0. > Is that right ? But Not the same with what you mean. The address mask applies only to matching a chip select. Once it's been matched, the full address goes to the device -- minus the bits that the device does not implement. An bit whose address mask is zero is treated the same as the least-significant 15 bits. > And from what you replied before in this question, may I say the 32KBytes will repeat through 4GiB address space ? not 8MBytes ? No. > then, what is the effect of CONFIG_SYS_MONITOR_BASE in this ABSOLUTE branch as uboot comment indicates ? The effect is that the program counter contains "CONFIG_SYS_MONITOR_BASE + in_flash", so that when the code later shrinks the chipselect it will still be executing from flash. -Scott