IIRC, For the the 2.4 kernel only supports the AT91RM9200DK and the 2.6 kernel separates the AT91RM9200DK and EK. so if you run on the EK (which most do, since the DK is obsolete) you have a problem doing both.
But the mach ID's for the AT91RM9200DK are the same in 2.4 and 2.6, right? So what is the problem? That there is no EK support in the 2.4 kernel? Well, many other recent processors / boards are not supported in 2.4 either. So use the kernel where the EK is supported - 2.6. I think it would be wrong to use fake mach ID's.
The 2.4 kernel is ín a maintenance phase, and I doubt that anyone will merge the AT91RM9200 patches into the 2.4 kernel ever. Whatif the patch depend on the AT91RM9200?
Sorry, I still don't understand what exactly is the problem.
Here is the relevant contents of mach-type.h
#define MACH_TYPE_AT91RM9200 251 -Used by Linux 2.4 #define MACH_TYPE_AT91RM9200DK 262 #define MACH_TYPE_AT91RM9200EK 705 - Used by Linux 2.6
So the first definition defines a SoC, not a board, so in theory for an AT91RM9200EK both 251 and 705 are correct.
This was probably not a good setup from the start, but the Linux-2.4 community is using 251. Linux-2.4 does not recognize 262 and 705. Linux-2.6 (correctly) does not recognize 251. If I want to work with a customer and exchange kernels, then I will have to request them to modify their source to a non-standard and only then can I solve their problem. Not a good idea to me.
There is another, more compelling reason for having this patch though. It is becoming more common for people to design System on Modules where you have a small board with CPU, Memory and maybe an Ethernet MAC. Customers would want these boards to be as ready as possible, and thus have both U-boot and Linux running. Then they add their own baseboard, and if they desire to register the combination as a new machine type. If they recompile the kernel using the new machine Id,then they have to recompile u-boot, for the single purpose of changing the machine type. Seems better to support changing the machine type using a setenv command.
Best Regards Ulf Samuelsson ulf@atmel.com Atmel Nordic AB Mail: Box 2033, 174 02 Sundbyberg, Sweden Visit: Kavallerivägen 24, 174 58 Sundbyberg, Sweden Phone +46 (8) 441 54 22 Fax +46 (8) 441 54 29 GSM +46 (706) 22 44 57
Technical support when I am not available: AT89 C51 Applications Group: mailto:micro.hotline@nto.atmel.com AT90 AVR Applications Group: mailto:avr@atmel.com AT91 ARM Applications Group: mailto:at91support@atmel.com FPSLIC Application Group: mailto:fpslic@atmel.com Best AVR link: www.avrfreaks.net