On 08.09.2008 05:54, ron minnich wrote: > On Sun, Sep 7, 2008 at 5:06 PM, Kevin O'Connor <[EMAIL PROTECTED]> wrote: > > >> 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. >> > > I don't want to revisit this if I don't have to :=) > > This discussion of "use old stack"/"use new stack" went on for a bit, > and we went with "use old stack" for a number of reasons. > One big reason was that our production bios experts told us we really > ought to be able to keep using the stack after disabling car, > and we have shown with v3 that this is possible BUT BUT BUT: > > we need to reserve 2x the active stack area (on entry to CAR) to > properly use the old stack on K8. Just FYI. >
Well, that's what the code requires now, but it is easy to change that without changing our working stack-backup-restore inline asm. We can back up the area clobbered by the stack backup before backing up the stack. The alternative of backing up the stack to a reserved area at the top of memory won't work due to inline asm peculiarities. > (NOT the whole CAR area, just the area of stack that is active when we > call disaable_car). > > This is easy but it's important to remember it. > For multiprocessor environments, these two are basically identical. Regards, Carl-Daniel -- http://www.hailfinger.org/ -- coreboot mailing list [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
