From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3CC79510.BF265F98@timesys.com> Date: Thu, 25 Apr 2002 11:03:04 +0530 From: ashish anand MIME-Version: 1.0 To: steven blakeslee , nanogui@linuxhacker.org, linuxppc-dev@lists.linuxppc.org Subject: Re: [nanogui] question concerning accessing RAM References: Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: check if by any chance you have missed ioremapping the lcd framebuffer steven blakeslee wrote: > > I'm working on a driver for embedded Linux 2.4 on a ppc board to use a 640 > by 480 LCD. I've been able to set up the lcd registers and register the new > frame buffer. The problem is every time I try to use the frame buffer I get > an error. > > Oops: kernel access of bad area, sig: 11 > NIP: C0107D7C XER: 00000000 LR: C0107D30 SP: C3AD7E70 REGS: c3ad7dc0 TRAP: > 0300 > MSR: 00009032 EE: 1 PR: 0 FP: 0 ME: 1 IR/DR: 11 > DAR: C0111380, DSISR: 82000000 > TASK = c3ad6000[80] 'nano-X' Last syscall: 5 > last math 00000000 last altivec 00000000 > GPR00: C0111380 C3AD7E70 C3AD6000 00000000 00000000 00000000 C3BD9AEC > C3BD9010 > GPR08: 0000001B C0111370 C3AD6000 38635619 24000022 10044D98 00000000 > 00000000 > GPR16: 00000000 00000000 00000000 00000000 00009032 03AD7F40 00000000 > C0002BC8 > GPR24: C00028E0 00000000 C01E6750 C3BD9A90 00000000 C025DA14 00000000 > C0262248 > Call backtrace: > C0107D30 C00A5088 C00573AC C00572B0 C0057800 C0002984 7C0802A6 > > I use alloc_bootmem_pages(PAGE_SIZE*75) to allocate the memory, I do this in > m8xx_setup.c. I get a pointer and use a for loop to modify the memory I > just allocated, when the kernel initializes the lcd registers the > appropriate color shows on the LCD. The problem is after the kernel boots I > am unable to modify this ram again. I have tried using the frame buffer and > also I have tried several modules. If anyone can give advice I would > appreciate it. ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/