From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Gehrlein Date: Wed, 01 Apr 2009 11:42:41 +0200 Subject: [U-Boot] ppc: using d-cache for C stack and as cache at the same time? In-Reply-To: <20090401091436.7163683797DC@gemini.denx.de> References: <49D323E5.9080100@tqs.de> <20090401091436.7163683797DC@gemini.denx.de> Message-ID: <49D33711.9040806@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 Dear Wolfgang Denk, Wolfgang Denk schrieb: > Dear Jens Gehrlein, > > In message <49D323E5.9080100@tqs.de> you wrote: >> 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). Why not? Of course, it's only possible if I can use a part of the D-Cache as C stack (or another internal RAM if available). This must be separately checked for each processor. > 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. Thank you for the hint. I'll have a look. > 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. I agree. Kind regards, Jens