From mboxrd@z Thu Jan 1 00:00:00 1970 From: Timur Tabi Date: Tue, 30 Mar 2010 10:21:33 -0500 Subject: [U-Boot] [PATCH v2] mpc86xx: set the DDR BATs after calculating true DDR size In-Reply-To: <28AF45F6-CF0E-4597-840A-F699C62BABE7@kernel.crashing.org> References: <1269959143-15581-1-git-send-email-galak@kernel.crashing.org> <4BB20CA8.30700@freescale.com> <28AF45F6-CF0E-4597-840A-F699C62BABE7@kernel.crashing.org> Message-ID: <4BB216FD.4070404@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 Kumar Gala wrote: >> We still have the problem that, on a 1.5GB system, U-Boot will think that there are 1.5GB of DDR, but the BAT will be set to 1GB. When U-Boot tries to relocate itself, it will machine check. >> >> We need a way to tell U-Boot that we only have 1GB of DDR, but still have it tell Linux that we have 1.5GB of DDR. > > is this situation you have today? (or just a concern?) Just a concern. Technically, we have the same problem on e500, except on e500 we use multiple TLBs to map the memory. In theory, we need at most one TLB/BAT per DIMM slot, which means we would need four BATS on the MPC8641 HPCN. Do we want to tell customers that U-Boot/Linux only supports power-of-two sizes of DDR? -- Timur Tabi Linux kernel developer at Freescale