From mboxrd@z Thu Jan 1 00:00:00 1970 Message-Id: <200008190826.KAA17158@denx.local.net> To: clark@esteem.com cc: linuxppc-embedded@lists.linuxppc.org Subject: Re: PPCBoot memory mapping problems From: Wolfgang Denk Mime-version: 1.0 Content-type: text/plain; charset=ISO-8859-1 In-reply-to: Your message of "Fri, 18 Aug 2000 17:45:01 PDT." <1.5.4.32.20000819004501.006984e4@pop.esteem.com> Date: Sat, 19 Aug 2000 10:26:22 +0200 Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Hi, in message <1.5.4.32.20000819004501.006984e4@pop.esteem.com> you wrote: > > I have hacked & slashed the PPCBoot code to work with our custom > board (all except the flash portion). I have mapped the memory as show below. Looks OK. > kernel. Following the instructions in the readme file, I grabbed > arch/ppc/coffboot/vmlinux.gz and converted as shown. It is given a load > address of 0x00000000 and an entry point 0x0000000C. I put the converted Be careful here! This depends on the kernel version! Entry point 0xC is/was used in "older" kernel versions like 2.2.13. This has changed in 2.3.x kernels, which started executing code form 0, so if you are running a 2.3 / 2.4 kernel make sure to set the entry point to 0x0. > Our board boots up checks the kernels CRC then uncompresses it. It > then jumps to 0x0000000C. A little bit later it then jumps to some address This is OK - as soon as the kernel switches on the MMU it will use virtual addresses. > 0xC000???? and faults. This may be casued by a bad entry point (see above), or you might be fooled if you're running with an ICE that does not work with MMU (make sure to set the DER to a sensible value, or use a better ICE). > Is this what it is supposed to do? Am I supossed to have the RAM The use of 0xC00xxxxx addresses is supposed to happen, the faults are not supposed to happen - if they really are. I guess it's just your ICE... > mapped at 0xC0000000? If it loads at address 0 how do I remap it to > 0xC0000000 once the kernel starts? Is there any way to force the kernel to > run in lower memory? You don't remap the RAM; the kernel will take care of address translation of virtual to physical addresses. Note 1: I'm not sure if too many people on the linuxppc-embedded mailing list are interested in PPCBoot issues; the ppcboot-users mailing list is probably a more appropriate place for such discussion. Note 2: Although not yet officially announced, ppcboot-0.4.3 is out (both on the CVS server and on our FTP server (ftp://ftp.demx.de/pub/ppcboot/ppcboot-0.4.3.tar.gz); on the CVS server there are even some more recent modifications in preparation of suport for some IBM 4xx based board. Hope this helps, Wolfgang Denk -- Software Engineering: Embedded and Realtime Systems, Embedded Linux Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd@denx.de I have a theory that it's impossible to prove anything, but I can't prove it. ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/