Actually it executes quite a lot of code in head.S, before it gets to start_kernel. Check to see if you can find out exactly where the problem occurs (for example, on the 74xx cpus, registers SRR0 & SRR1 have this info).
> Folks, > > I just wanted to provide more info on my env. I have > PPC405 based board with no network support forcing me > to use zImage.initrd.elf. > > Can you suggest more on my problem described below? I > saw the memory values at 0x00000000 onwards after > uncompressing linux and they have changed. But when > the control jumps to 0x0, my board hangs. I see that > ESR is showing a value of 0x80000000, meaning either > illegal instruction or Machine Check. > > Can you tell what's going on? What happens next after > uncompressing? I am thinking it executes start_kernel > function which calls lock_kernel. Let me know if i am > wrong. > > thanks, > Prakash > > --- James Don <JDon at spacebridge.com> wrote: > > I just went thru this myself ... ;-) > > > > 1.) Get a BDM/JTAG tool look halt the processor > > after you see " Now booting > > the kernel" and look for valid asm at 0x0 ... make > > sure it mathes your > > start.s file ... > > > > 2.) Veryfy you have your mem map from ppcboot > > matching requirements for the > > kernel i.e ram (physical=0x0, virtual=0xc0000000) > > and immr (phys 0xff000000 > > virtual 0xff000000) ... I had my immr in ppc boot at > > 0x02200000 this screwed > > me for quite a while ... otherwise you have no > > printk ... the memory map is > > very important not to screw with some things depend > > on it (unless your > > careful) ... > > > > 3.) verify you SMC1 (uart) is getting proper > > clocking config ... i.e > > bus->brg1 and brg1 is 16 times baud rate ... > > otherwise you have no printk > > > > 4.) and always always keep in mind your RAM refesh > > could be wrong ... > > everyone will tell you this even when it has nothing > > to do with your problem > > ... try not to ignore them if you are still stuck > > ;-) But verifying step 1 > > should prove your ok ... > > > > Best of luck, > > Jim > > > > > > -----Original Message----- > > From: Prakash kanthi [mailto:pkanthi at yahoo.com] > > Sent: Wednesday, December 18, 2002 7:14 PM > > To: LinuxPPC > > Subject: After Uncompresseing Linux..., what's next > > > > > > Hi there, > > > > I was trying to load linuxppc_2_4_devel onto my > > board. > > It goes through the board info read, UART init and > > Uncompressing the linux kernel. But after that, i do > > not see any messages and board hangs. > > > > Here is the UART output: > > ------------------------------------ > > OS Booting... > > > > loaded at: 00400000 0060D1CC > > board data at: 00000030 00000044 > > relocated to: 00405C24 00405C38 > > zimage at: 00406290 004A08FF > > initrd at: 004A1000 006097CA > > avail ram: 0060E000 007F8000 > > > > Linux/PPC load: console=ttyS0,9600 console=tty1 > > ip=on > > root=/dev/xsysace/disc0/pa > > rt3 rw > > Uncompressing Linux...done. > > Now booting the kernel > > ------------------------------------------- > > > > After the last line, it hangs. I get a feeling that, > > the uncompressing process is not writing in the > > memory > > starting from 0x00000000 and, after uncompressing, > > it > > is jumping into 0x00000000 and is not able to find > > anything. > > > > My questions are, > > 1. How can i make sure that, the uncompressing > > process > > is going to start writing the data from 0x00000000. > > > > 2. How big a space this uncompressing process needs? > > And also how much overall memory is required for > > running linux. I just have 8MB SDRAM. > > > > 3. What is the next step in the booting process? > > Which > > Device (eth, pci, ide, ???) Initialization? > > > > Your help is appreciated. > > > > thanks, > > Prakash > > > > > -- Sincerely, Jim Potter 45th Parallel Processing Firefighting: Bustin' ours, Savin' yours. ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
