Hi, On Sun, Sep 07, 2008 at 10:59:13PM +0200, Carl-Daniel Hailfinger wrote: [...] > CAR will write to memory locations below 1M. There are three ways to > cope with that: [...] > 3. Write excessively clever and fragile code which performs a double > stack switch during resume. [...] > 3. Will NOT work for Geode, may not work for Intel and VIA. The existing > CAR enabling/disabling code will seem trivial in comparison.
Why can't the code use a new stack after CAR is disabled? To be clear, I think moving the stack would be a bad idea. However, I don't see why the code can't just start using a new stack. Right now, the only stack variable that is shared between CAR and post-CAR is 'archive' (in stage1_main() ). I would think one could manually copy it from the CAR stack to a post-CAR global variable. (Or just rebuild it from scratch.) I'm thinking - one could implement a small assembler trampoline function that took two parameters - the new stack location and the function to jump to. The assembler would only need to set %esp and jump to the new function. This would still require memory under 1MB for car, but at least stage2 could run with a full stack and globals that run in reserved memory. Have I missed something? -Kevin -- coreboot mailing list [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
