Hi All,
I have got a new bdi2000 to help me in debugging linux kernel. I have been able to successfully run u-boot on MPC7455 based custom board. My problem is that I am not able to get bdi2000 to work properly with my system. To help me shortlist candidates for the errors I am getting, I would like your help in understanding what I am doing wrong here.
I reset the processor using bdi command line, the processor remains in halted state until I ask it to "go"
BDI>info Target CPU : MPC7455 Rev.2 Target state : debug mode Debug entry cause : COP freeze (startup) Current PC : 0xfff00100 Current CR : 0x00000000 Current MSR : 0x00000000 Current LR : 0x00000000 BDI>go
After some secs, I could see U-Boot messages on the serial port on the board. At some point in time, I halt the processor. BDI>halt Target CPU : MPC7455 Rev.2 Target state : debug mode Debug entry cause : COP halt Current PC : 0x00fe51bc Current CR : 0x24000000 Current MSR : 0x00000030 Current LR : 0x00fe4f60
Then, on my host machine I startup the gdb, discard the symbol file. U-Boot was linked at 0x1ff0000, after relocation it runs at 0xfe0000. So I reload the symbol file with the offset 0xfe0000.
simpod:[~/develop/u-boot]$ powerpc-linux-gdb u-boot GNU gdb 6.0 This GDB was configured as "--host=i686-pc-linux-gnu --target=powerpc-linux"... (gdb) symbol-file Discard symbol table from `/home/sharad/develop/u-boot/u-boot'? (y or n) y No symbol file now. (gdb) add add-shared-symbol-files add-symbol-file (gdb) add-symbol-file u u-boot u-boot.bin u-boot.dump u-boot.map u-boot.memh u-boot.mif u-boot.srec (gdb) add-symbol-file u-boot 0xfe0000 add symbol table from file "u-boot" at .text_addr = 0xfe0000 (y or n) y Reading symbols from u-boot...done.
Case I -> I attach it to the bdi ... It tells me where exactly is the processor halted. I set the breakpoint at do_bootm ... I say continue to gdb ... go to my serial port on the board, ask it to do "bootm 3000000 4000000" ... but I never see the breakpoint becoming active on gdb .... it just continues loading the linux ...
(gdb) target remote bdi:2001 Remote debugging using bdi:2001 0x00fe51bc in NS16550_getc (com_port=0x60000000) at ns16550.c:53 53 while ((com_port->lsr & LSR_DR) == 0); (gdb) mon break Breakpoint mode is SOFT (gdb) b do_boot do_bootm do_bootm_linux do_bootm_netbsd do_bootm_rtems (gdb) b do_bootm Breakpoint 1 at 0xfe6488: file cmd_bootm.c, line 149. (gdb) c Continuing.
Case II -> In another instance, I get the following error when I insert breakpoint at NS16550_getc routine:
(gdb) target remote bdi:2001 Remote debugging using bdi:2001 0x00fe51c4 in NS16550_getc (com_port=0x60000000) at ns16550.c:53 53 while ((com_port->lsr & LSR_DR) == 0); (gdb) b NS NS16550 NS16550_init NS16550_reinit NS16550_tstc NS16550_getc NS16550_putc NS16550_t (gdb) b NS16550_getc Breakpoint 1 at 0xfe51b8: file ns16550.c, line 53. (gdb) mon break Breakpoint mode is SOFT (gdb) c Continuing.
Breakpoint 1, NS16550_getc (com_port=0x60000000) at ns16550.c:53 53 while ((com_port->lsr & LSR_DR) == 0); (gdb) step
Program received signal SIGSTOP, Stopped (signal). Cannot remove breakpoints because program is no longer writable. It might be running in another process. Further execution is probably impossible. 0x00fe51c0 in NS16550_getc (com_port=Cannot access memory at address 0xfbee48 ) at ns16550.c:53 53 while ((com_port->lsr & LSR_DR) == 0); (gdb) step
Program received signal ?, Unknown signal. Cannot remove breakpoints because program is no longer writable. It might be running in another process. Further execution is probably impossible. 0x00fe51c0 in NS16550_getc (com_port=Cannot access memory at address 0xfbee48 ) at ns16550.c:53 53 while ((com_port->lsr & LSR_DR) == 0);
Any help would be highly appreciated. Thanks Sharad.