All, I'm doing an "off the books" project here at work to bring up Linux on one of our in-house designed targets. We have several designs that share the same core architecture: MPC850 @ 80 MHz., 32 M-byte SDRAM, 4 M-byte boot flash, SMC console, and Ethernet. These designs are quite stable and already in production. We also have visionICE/visionCLICK debugging tools.
Our low-level boot code sets up the UPMA table and the basic address map (SDRAM at 0x00000000, IMMR at 0xfb000000, FLASH at 0xffc00000), moves an image from either FLASH or UDP/IP/Ethernet into SDRAM, turns off all I/O, and jumps to the loaded image. All of this works quite nicely with our current production software. Switching to u-boot at this point is not a desirable option. Because of the similarity to our targets, I've built an RPXLite image from Rev. 4.2.19 sources. I have made modifications of the sources to accommodate differences between our board and the RPXLite (e.g., we don't have a configuration register). I have also built a root filesystem image from the sources available on the "www.embeddedlinuxinterfacing.com" web site. All of this has been combined into a single compressed image and all looks good. When I run this image it hangs in panic. I don't have console I/O yet. No joy in Mudville. My strategy has been to put whatever code is necessary at the beginning of "linux/arch/ppc/boot/simple/head.S" to make the compressed image think it just got control from u-boot. Since I have the SDRAM setup at location 0x00000000 and the FLASH and IMMR are up high out of the way, this seems reasonable. I've found definitions for the bd_info structure in "linux/include/asm/rpxlite.h" and in "linux/include/asm/ppcboot.h". I believe I've setup a bd_info structure as specified in "ppcboot.h" since this matches "u-boot-0.2.0/include/asm-ccp/u-boot.h". I'm still not sure I've got everything setup correctly. Question: Is there a specification of how the compressed Linux image expects an MPC8xx system to be set up (i.e., a requirements spec.) or is "linux/.../ppcboot.h" and "u-boot/.../u-boot.h" it? Does the SMC need to be initialized? How about Ethernet?, etc., etc. Any guidance would be appreciated. Regards, Charlie Charles.Wells at NielsenMedia.com 727.738.3000 ext.2756 ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
