Hi Folks, I think finally i have idea as to why boot process was failing. After uncompressing linux image, the code execution was aborting with an ESR value of 0x08000000, which stands for "ILLEGAL INSTRUCTION". When i checked the instruction causing this, i figured that, 'tlbia' (0x00002384) is the culprit. tlbia is a valid instruction in PPC405 instruction set.
I still don;t understand, how come it is getting rejected. Am i missing anything? Can anyone please throw some light on this? thanks, Prakash --- Prakash kanthi <pkanthi at yahoo.com> wrote: > > Gary, > > I really appreciate your help. Here is what i am > doing. Sorry it is little long. But was necessasry. > > 1. I have a boot loader(xrom.elf) of size around > 400KB > which basically have menu driven tests along with an > option to jump to linux kernel(zImage.initrd.elf). > > 2. xrom.elf is compiled to start at 0xfffffffc and > jump to 0x00000000 to have rest of functionality. > zImage.initrd.elf is compiled to start at > 0x00400000. > > 3. I load zImage.initrd.elf first and then xrom.elf > (xilinx tool makes sure that they are loaded to > corresponding locations based on ELF header). > > 4. After loading both, i start running xrom.elf and > it > shows up a menu in my UART terminal. I jump to linux > (0x00400000). > > 5. I see that linux is basically reading the board > info, setting UART, prints some boot messages onto > it > and then performs uncompression (gunzip function > takes > the rest of linux image and puts the uncompressed > code > starting from 0x0). > > 6. Up untill, everything is ok. After this, control > jumps to 0x0 and starts executing. > > My problems are, > > a. Once the uncompression process is done, i am not > sure if the image is copied to 0x0 (i do see value > changes in memory starting from 0x0). > b. As uncompression process is embedded into > zImage.initrd.elf, i do not objdump does not tell me > which function it is going to execute after > uncompression. > > Please suggest. > > Thanks, > Prakash > > > > > > --- Gary Thomas <gary at chez-thomas.org> wrote: > > On Fri, 2002-12-20 at 09:48, Prakash kanthi wrote: > > > I do have xilinx tools and i am working with > their > > V2P > > > product. I completely understands what you are > > said. > > > But the problem is, right after the > uncompression > > and > > > cpy to 0x00000000, i loose total control because > i > > > don't have any clue what is getting executed. > > > > > > > What sort of things can you do with the Xilinx > > tools? Is > > there any way to set [hardware] breakpoints or > > single step? > > > > > And also, i have my boot monitor code at > > 0x00000000, > > > before uncompress process overwrites it. I see > > that > > > some of that code is getting executed after jump > > to > > > 0x0. I reason i am overwriting 0x0 is because, i > > only > > > have 8MB RAM. > > > > > > > 8M should be plenty of RAM. > > > > > > > ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
