I did this once on a mpc860 board. It involved running the uncompressed kernel image through vxhack.c from Dan Malek with a few fixes since the segments seemed to have moved around. The VxWorks loader would then load the hacked image through bootp or tftp. I also had to have one of the Linux bootloader files initialize a bd_t structure. I was able to poke around in memory and find where the VxWorks loader was keeping the environment.
Don Dave Strout wrote: > > Thanks all for the help with the toolchain -- I'm now cranking out ppc > code. > > Now to boot. What I'm actually trying to do is replace a VxWorks > environment on one of my companies products with Linux. The unit is > 405GP based, and pretty close to a walnut, as far as I can tell > (comparing the mem map in the docs with the 405gp.h file in the > kernel). I'm hoping to get away with using the existing boot monitor, > at least in the short term. The monitor has the ability to load an ELF > executable & jump to it, but I'm not getting very far beyond that -- in > fact it crashes with the pc at the first instruction. I've tried my > freshly-built 2.4.18 kernel, and the ppcboot executable, and they both > crash on the first instruction. > > I don't have a hardware debugger for this, so I'm sort of at a loss. > There are some LED's on the front that I could try & write some asm to > blink as I go along, but since I hang on the first instruction, I'm not > sure that would help....... > > All thoughts greatly appreciated. > > dave. > > > Dumps: > > Linux: > ftp 134.141.133.254:vmlinux to SDRAM size=1430968 > Booting system S/W at entry 0xc0000000 > Starting at 0xc0000000... > > > program > Exception current instruction address: 0xc0000000 > Machine Status Register: 0x00029200 > Condition Register: 0x24200082 > Task: 0x1f1a8e0 "tBoot" > > r0 = c034dc sp = 1f1a4d0 r2 = 0 r3 > = 0 > r4 = 1f80000 r5 = 1f1a8e0 r6 = 29200 r7 = > 1200 > r8 = 20 r9 = ca0000 r10 = 4 r11 > = 0 > r12 = 0 r13 = 0 r14 = 0 r15 > = 0 > r16 = 0 r17 = 0 r18 = 0 r19 > = 0 > r20 = 0 r21 = 0 r22 = 0 r23 > = 0 > r24 = 0 r25 = 0 r26 = 0 r27 = > ca0000 > r28 = ca0000 r29 = c0000000 r30 = 1ffffc8 r31 = > c0000000 > msr = 29200 lr = c034e4 ctr = 0 pc = > c0000000 > cr = 24200082 xer = 0 > > ppcboot: > > ftp 134.141.133.254:ppcboot to SDRAM size=186232 + 4 > Booting system S/W at entry 0xfff80000 > Starting at 0xfff80000... > > > program > Exception current instruction address: 0xfff80000 > Machine Status Register: 0x00029200 > Condition Register: 0x24200082 > Task: 0x1f1a8e0 "tBoot" > > r0 = c034dc sp = 1f1a4d0 r2 = 0 r3 > = 0 > r4 = 1f80000 r5 = 1f1a8e0 r6 = 29200 r7 = > 1200 > r8 = 20 r9 = ca0000 r10 = 4 r11 > = 0 > r12 = 0 r13 = 0 r14 = 0 r15 > = 0 > r16 = 0 r17 = 0 r18 = 0 r19 > = 0 > r20 = 0 r21 = 0 r22 = 0 r23 > = 0 > r24 = 0 r25 = 0 r26 = 0 r27 = > ca0000 > r28 = ca0000 r29 = fff80000 r30 = 1ffffc8 r31 = > fff80000 > msr = 29200 lr = c034e4 ctr = 0 pc = > fff80000 > cr = 24200082 xer = 0 > > Objdump says: > [dstrout at dstrout dstrout]$ ~/tools/bin/powerpc-linux-objdump -D ppcboot > | head -20 > > ppcboot: file format elf32-powerpc > > Disassembly of section .resetvec: > > fffffffc <.resetvec>: > fffc: 4b f8 01 04 b fff80100 <_start> > Disassembly of section .text: > > fff80000 <version_string-0x4>: > fff80000: 27 05 19 56 dozi r24,r5,6486 > > fff80004 <version_string>: > fff80004: 50 50 43 42 rlwimi r16,r2,8,13,1 > fff80008: 6f 6f 74 20 xoris r15,r27,29728 > fff8000c: 31 2e 31 2e addic r9,r14,12590 > fff80010: 35 20 28 4a addic. r9,r0,10314 > fff80014: 75 6e 20 20 andis. r14,r11,8224 > fff80018: 35 20 32 30 addic. r9,r0,12848 > fff8001c: 30 32 20 2d addic r1,r18,8237 > > [dstrout at dstrout dstrout]$ ~/tools/bin/powerpc-linux-objdump -D vmlinux > | head -20 > > vmlinux: file format elf32-powerpc > > Disassembly of section .text: > > c0000000 <_start>: > c0000000: 7c 7f 1b 78 mr r31,r3 > c0000004: 7c 9e 23 78 mr r30,r4 > c0000008: 7c bd 2b 78 mr r29,r5 > c000000c: 7c dc 33 78 mr r28,r6 > c0000010: 7c fb 3b 78 mr r27,r7 > c0000014: 3b 00 00 00 li r24,0 > c0000018: 48 00 23 49 bl c0002360 <initial_mmu> > > c000001c <turn_on_mmu>: > c000001c: 38 00 10 32 li r0,4146 > c0000020: 7c 1b 03 a6 mtsrr1 r0 > c0000024: 3c 00 c0 00 lis r0,-16384 > c0000028: 60 00 22 c0 ori r0,r0,8896 > c000002c: 7c 1a 03 a6 mtsrr0 r0 > > > ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
