OK Does that mean that I cannot debug the source until after the MMU is turned on?
-----Original Message----- From: Wolfgang Denk [mailto:[EMAIL PROTECTED] Sent: Friday, October 10, 2003 2:01 PM To: Joao Vicente Cc: linuxppc-embedded at lists.linuxppc.org Subject: Re: Problem debugging ppc kernel with DDD/GDB/BDI2000 on a custom MPC8260 board Dear Joao, in message <DEF39A0710293E489D45B10E06645CBD0243B232 at dub-msx1.spectelcorp.com> you wrote: > > Once inside gdb, I am typing 'target remote 10.121.10.22:2001' after > which I am obtaing the following output: > 0x00000000 in ?? () OK. > One thing I cant get my head around is that if the system.map file > shows _start address at 0xc000000, how can the gdb relate the symbols on > vmlinux, assuming they are are expected to be at 0xc0000000? 0xC....... is a kernel virtual address which will be valid as soon as Linux turns on the MMU (which it does very early durin initialization). > I have also tried to load the symbol file at 0x00000000 with the > 'add-symbol-file vmlinux 0x00000000' followed by 'target remote > 10.121.10.22:2001'. Does this make any sense if the code is not > relocatable ? No, this makes no sense. > My intention here is not to have this build to work with my board, but > to just be able to display the symbols and trace the flow of the kernel, > so that I can then start customising it for the custom hardware. Ummm... In my experience a better approach would be to figure out the necessary changes _before_ even attempting to boot the kernel. Inter- preting the effects of a misconfigured kernel it not exactly easy as funny things might happen. > In order to customise the build for my board, what would be your > sugestion. Should I modify config.in in order to launch an independent Yes. Create a new configuration option for your board. > config on the build, or use one of the given ones and hard code a > XXX_CONFIG specific for my board onto include/linux/autoconf.h or some Modifying include/linux/autoconf.h makes no sense. This file gets automagically created dureing the kernel config & build steps. > For instance, I have noticed that there is specific CONFIG_ADS8260 > #ifdefs throughout the ppc arch source, but no standard configuration is > available from 'make menuconfig'. Is this because this board's port is > not complete, or should a default config be selected on menuconfig, and > the CONFIG_ADS8260 added into a top header file ? My guess is that this port was only completed in more recent versions of the (linuxppc_2_4_devel) kernel tree. > The u-boot README file is an excellent source of documentation for > porting the u-boot for custom boards, which has been extremelly helpful > on my exercise on porting u-boot (along with your kind guiding help). > Do you know of any similar documentation as far as customising the > kernel for a custom board ? Except for the source code, no. Best regards, Wolfgang Denk -- Software Engineering: Embedded and Realtime Systems, Embedded Linux Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd at denx.de Philosophy is a game with objectives and no rules. Mathematics is a game with rules and no objectives. ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
