Hi, I am attempting to get Kernel debugging working on our mpc8541 based board via a BDI2000. The various components in use are
kernel - 2.6.19.2 BDI firmware - 1.08 U-Boot - 1.2.0 ppc_85xx-gdb - from eldk4.1 (6.3.0.0-1.21_3rh) Kernel is configured with `-g` in CFLAGS and not with CONFIG_BDI_SWITCH, from the information I have read around the subject this seem to be correct. I also have `MMU XLAT`, and `PTBASE 0xF0` set in by BDI configuration file. The default value for XLAT of `0xc0000000` matches the kernel our kernel config. Steps that I done so far 1. Power on BDI 2. Power on the board 3. BDI> reset run 4. Enter u-boot environment to stop linux booting immediately. 5. BDI> HALT 6. BDI> BREAK HARD 7. BDI> BI 0xc025a51c (this is the address of start_kernel for my build) 8. BDI> GO 9. From U-boot prompt `bootm`, kernel is copied from flash and loading begins 10. Kernel does not halt at start_kernel and continues to the login If I attempt to break at an address later in the boot sequence, such as qmx19_ata_input_data (this is the area that I am trying to investigate) I get - TARGET: core #0 has entered debug mode So from here I attempt to connect to the BDI from gdb linux> cd ~/linux-2.6.19.2 linux> ppc_85xx-gdb vmlimux " GNU gdb Red Hat Linux (6.3.0.0-1.21_3rh) Copyright 2004 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "--host=i386-redhat-linux --target=ppc-linux". The target architecture is set automatically (currently powerpc:603) " I noticed here that the last line does not match the e500 core I am using, but there does not seem to a change if I change this using `set architecture powerpc:e500` (gdb) tar rem <bdi_ip>:2001 Remote debugging using <bdi_ip>:2001 0x00000000 in ?? () What I don't understand here is why 0x00000000 is shown as the address, further on the BDI the following error is shown then the connection is made " *** MMU: address translation for 0x00000000 failed *** MMU: address translation for 0xFFFFFFFC failed *** MMU: address translation for 0x00000000 failed *** MMU: address translation for 0xFFFFFFFC failed " If I then clear the breakpoint from the BDI BDI> CI I can then from gdb set breakpoints (gdb) b qmx19_ata_input_data Breakpoint 1 at 0xc014ecb4: file drivers/ide/ppc/qmx19-ide.c, line 139. (gdb) c Continuing. And all seems well with resolving the symbol names and and source files. When the breakpoint is hit next " Program received signal SIGTRAP, Trace/breakpoint trap. 0x00000000 in ?? () (gdb) where #0 0x00000000 in ?? () #1 0x00000000 in ?? () " But as expected I can not do any debugging since the address's are not being resolved by GDB/BDI. Trying to single step now results in gdb showing (gdb) s Cannot find bounds of current function and BDI showing *** MMU: address translation for 0x00000000 failed *** MMU: address translation for 0xFFFFFFFC failed So my problem would seem to be with address translation. If I ask the BDI to translate the address for me it seems fine though BDI> PHYS 0xc014ecb4 PHYS = 0x0_0014ecb4 So in summary is seem to me that there is a problem with the address translation to from BDI GDB, most likely the result of a missing configuration parameter or setting. I should also add that there there is not an inherent problem with the build of Linux as it boots fine and is operational but I would like to step though our CF card driver when the kernel is loading. I have seen a couple of similar questions asked regarding the mpc85xx series but not any answers that have shed any light, by all accounts the steps I have done would seem to just work for other people, such as the BDI manual. Does anyone have some insights into this. thanks Stuart Hodgson _______________________________________________ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded
