Flashing LinuxBIOS on A-Test Boards
Warnings
YOU CAN BRICK YOUR MACHINE IF YOU FOLLOW ANY OF THESE STEPS!
The instructions here are for the A test boards. You can place an PLCC EEPROM into the (only) socket on the A test board, flash it with LinuxBIOS, and on reboot boot from the EEPROM chip containing your newly flashed LinuxBIOS. For now, this only covers flashing a PLCC chip.
Hardware
Currently there isn't any sane way to flash the ROM to the serial flash on the OLPC board without running a huge risk of bricking it. The only way to try out the ROM image right now is to write the image to a PLCC ROM chip and use that in the PLCC socket on the Rev A boards.
You will want to use 8Mbit ROM chips, like these.
Boot with normal BIOS and setup toolchain
Use your normal serial BIOS (currently, by Insyde Software) to boot into a Linux distribution. You'll need to build some software before you can flash your EEPROM chip with LinuxBIOS.
rdmsr
Build the rdmsr (read MSR) tool by Ron Minnich:
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
int main (int argc, char *argv[])
{
unsigned char buf[8];
int fd_msr, i;
unsigned long addr = 0;
if (argc < 2) {
printf("usage:rdmsr reg\n");
exit(1);
}
addr = strtoul(argv[1], NULL, 0);
fd_msr = open("/dev/cpu/0/msr", O_RDONLY);
lseek(fd_msr, addr, SEEK_SET);
read(fd_msr, buf, 8);
printf("MSR register 0x%lx => ", addr);
for (i = 7; i > 0; i--)
printf("%2.2x:", buf[i]);
printf("%2.2x\n", buf[i]);
return(0);
}
with:
% gcc rdmsr.c -o rdmsr
wrmsr
Build the wrmsr (write MSR) tool (also by Ron Minnich):
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
int main (int argc, char *argv[])
{
unsigned char buf[8], *p;
int fd_msr, i;
unsigned long addr = 0;
if (argc < 3) {
printf("usage:wrmsr reg value\n");
exit(1);
}
addr = strtoul(argv[1], NULL, 0);
p = argv[2];
printf("MSR register 0x%lx => ", addr);
for (i = 7; i > 0; i--) {
buf[i] = strtol(p, &p, 16);
p++;
printf("%2.2x:", buf[i]);
}
buf[i] = strtol(p, &p, 16);
printf("%2.2x\n", buf[i]);
fd_msr = open("/dev/cpu/0/msr", O_WRONLY);
lseek(fd_msr, addr, SEEK_SET);
if (write(fd_msr, buf, 8) < 0)
perror("");
return(0);
}
with:
% gcc wrmsr.c -o wrmsr
flashrom
Download the latest LinuxBIOS snapshot to get the flashrom utility. Unpack the archive, and go into the util/flashrom directory. After making sure you have your distribution's pciutils and pcituils-dev package installed, run make. This will build the flashrom utility; copy it into a convenient location (such as /usr/local/bin).
Using Flashrom
Enable writing to flash
On Linux, make sure you:
% modprobe msr
so you will have MSR device files. To enable PLCC writing on the OLPC board, you need to enable flash writing. Once you've built rdmsr and wrmsr, run:
./rdmsr 0x1808
./wrmsr 0x1808 22:ff:80:02:10:f7:bf:00
./rdmsr 0x1808
Using flashrom
Once you've got flashrom working, you can now flash your LinuxBIOS image. Check that flashrom can see your writable flash chip:
% flashrom -V
You should see a note about a writable part being detected. If so, you can now write to the part, with the LinuxBIOS image you've built previously:
% flashrom -w linuxbios.rom
Once it's written, verify that it has been written properly:
% flashrom -v linuxbios.rom
Boot with LinuxBIOS
You can now reboot. Make sure you shutdown properly (your disk/filesystems must be in a consistent state, and been unmounted properly). On reboot you'll be greeted by the OLPC LinuxBIOS splash screen, where you can select boot method. Choose USB to boot from a USB disk, hopefully using one of the build images.