Programming the SPI FLASH: Difference between revisions
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The OLPC LinuxBIOS includes an "olpcflash" utility which lets you reprogram the main SPI FLASH that contains LinuxBIOS and the microcode for the EC controller chip. |
The OLPC LinuxBIOS includes an "olpcflash" utility which lets you reprogram the main SPI FLASH that contains LinuxBIOS and the microcode for the EC controller chip. |
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Latest revision as of 23:17, 6 June 2007
The OLPC LinuxBIOS includes an "olpcflash" utility which lets you reprogram the main SPI FLASH that contains LinuxBIOS and the microcode for the EC controller chip. LayoutThe spansion 25FL008A SPI 1 MiB flash on the unit is divided into 2 main areas.
The EC (Embedded Controller) area is where the code for the 8051 uP in the EC lives. Changing the code in this area, unless you really know what you are doing and are prepared to deal with the breakage that can occur, is a Very Bad Thing. There is currently not a recovery method if you trash your EC code. Because of this, olpcflash does not mess with the first 64KiB of the part. Usage
To Read the LinuxBIOS area. $ olpcflash -r filename To Write the LinuxBIOS area. (Write will erase the area first) $ olpcflash -w filename To Verify the contents of the LinuxBIOS area vs a file. $ olpcflash -v filename If the verify fails, do not power off or reboot your machine as you may not be able to reboot if the flash has been corrupted; please reattempt to write and verify the flash. If the write/verify operations continue to fail, please get help. A good channel for help is the #OLPC IRC channel on irc.freenode.net. The method used during developement/testing was to link olpcflash staticly and copy it to a USB key. Then using a serial console, boot under the buildrom env from PLCC, mount the USB key, and run olpcflash. Olpcflash is currently being incorporated into buildrom and various root image files. Look for it soon in your favorite image. Known Issues
Adding them is on the TODO list. Think twice, flash once.
Part of the programming sequence is to place the EC's 8051 uP in reset to keep it from conflicting with the program cycles. This disables PS/2 keyboard/mouse. The uP is left in reset after olpcflash is finished. This prevents the possibility of the EC running code you may have just corrupted. You must reboot to restore PS2 keyboard/mouse.
How to do it the first timeSo how can you get it going before you have an olpcflash-equipped LinuxBIOS installed? If you have the ability to program PLCC FLASH chips for the OLPC board (see Flashing LinuxBIOS), you can build the latest LinuxBIOS (see Building LinuxBIOS), load it into a PLCC FLASH, then boot from that. Otherwise, you'll have to build olpcflash.c from source, put the executable file onto an external device like a USB disk, then run it under a Linux environment. You can get the latest source code from the buildrom tree (see Building LinuxBIOS) in work/olpcflash/olpcflash/olpcflash.c . To compile standalone: gcc -O olpcflash.c -o olpcflash If you link under glibc, yet want to run it under the uClibc based buildrom env, then you will need to add the -static option As stated earlier, olpcflash should start showing up as a standard command in OLPC images so building from source is probably not necessary. |