From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Gehrlein Date: Wed, 01 Apr 2009 11:47:36 +0200 Subject: [U-Boot] ppc: using d-cache for C stack and as cache at thesame time? In-Reply-To: References: <49D323E5.9080100@tqs.de> <20090401091436.7163683797DC@gemini.denx.de> Message-ID: <49D33838.2040309@tqs.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Liu Dave-R63238 schrieb: >>> AFAIK, while running from flash, u-boot uses (part of) >> d-cache on some >>> platforms for the C stack. I think, it's on MPC83xx and MPC85xx? >>> >>> Does anybody know, if I can use the remaining part of the d-cache >>> as normal d-cache, e.g. to generate bursts on the SDRAM interface >>> while testing the RAM? >> On which platform? >> >> Note that implementing a memory test that actually triggers burst >> mode accesses is really, really tricky. You probably do NOT want to >> do this while running from flash (i. e. from a very restrictive >> envrionment). You might want to have a look at examples/test_burst* >> but note that this code was written for a MPC8xx system, so changes >> will be required for 83xx or 85xx. >> >> Also note that a much more reliable test for burst mode errors is to >> boot Linux with root file system over NFS and then compile the Linux >> kernel on the target. > > It needs case by case. > > * 83xx, the whole d-cache is locked > If you need generate bursts on DRAM interface, you have to change to > way locked. Otherwise, you can use the DMA to generate burst. Good idea. > * 85xx, half of d-cache is locked. > it is possible to generate the burst at 85xx. > Try to use dcbf.... Thank you for the hints. Kind regards, Jens