Hi, I'm pretty new to PPC but I was following this newsgroup for some time. I've got PPC405 on a custom design board and I'd like to debug the reason why my linux kernel doesn't work on it. I've downloaded the latest kernel sources (2.4-devel) so there is no problem with missing or broken 405 support on it. I wanted to use UART0 for debugging purposes, so I've created simple C function sending a character to a physical PLB address of UART0 (this function doesn't use stack for sure, a character to be send is being passed via R3). I'm accessing physical memory using writel() and readl() macros. The idea seems to be OK.
I put a few my function calls into head_4xx.S file and everything seems to work (I could see characters on minicom) till the kernel started to execute after 'start_here' label. I know that at this stage kernel's addresses were remapped from 0x0000xxxx to 0xc000xxxx (am I right?) due MMU being enabled by 'turn_on_mmu'. So I remapped UART's memory space by 'io_block_mapping' - but this didn't help. What's going on ? Why I'm not seeing characters now ? Did the kernel hang somewhere in the middle or am I tottaly wrong in the early debugging idea ? Thanks for any help, Krzysztof -- Encyklopedia multimedialna w prezencie! http://www.e-mail.onet.pl ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
