From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Roese Date: Mon, 11 May 2009 15:31:11 +0200 Subject: [U-Boot] [PATCH v2] ppc4xx: Add Sequoia RAM-booting target In-Reply-To: <20090511132010.86983832E416@gemini.denx.de> References: <1242035235-26833-1-git-send-email-sr@denx.de> <200905111339.28531.sr@denx.de> <20090511132010.86983832E416@gemini.denx.de> Message-ID: <200905111531.11474.sr@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Monday 11 May 2009 15:20:10 Wolfgang Denk wrote: > > > And what happens when the TLB is not correctly set? Will we get a > > > useful error message then? > > > > No. SDRAM needs to work correctly so that this RAM-booting version can > > function. And for this the MMU needs to be configured and the SDRAM > > controller setup correctly. If this is not the case and SDRAM is not > > working from the debugger then we have no chance to load this image > > without problems (verify will most likely fail) or run it. > > Hm... if the image cannot run anyway without initialized SDRAM TLB, > then why do you scan for it? My understanding is that the result > wouldbe the same even if you omitted this test: without initialized > SDRAM TLB the system would just hang / crash without error message. > So this test is dead code. > > Or am I missing something? I'm "scanning" for the SDRAM TLB, because it can be on any TLB location. In my first implementation I assumed that the SDRAM TLB was TLB #0 (configured via BDI2000). This worked just fine. But then I loaded this RAM-booting image via U-Boot and started it here (via go ...). And it crashed since U-Boot uses a different TLB #. So now I'm scanning/detecting the SDRAM TLB to be independent from the originator of the TLB. Best regards, Stefan ===================================================================== DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: +49-8142-66989-0 Fax: +49-8142-66989-80 Email: office at denx.de =====================================================================