On Thu, 16 May 2002 20:34:07 -0400, Jim Houston <[EMAIL PROTECTED]> wrote: >The attached patch is an update of my earlier patch >to fix smp problems in kdb. I started with Ethan >Solomita's patch but I have change a lot of code >since then. I have been exchanging private email with >Ethan over the last week and he has helped find some >of my bugs. Thanks again. There are always more bugs >but I think this patch has reached the useful stage.
I finally got time to spend on kdb, my apologies for not answering these patches sooner. Jim, Ethan, is this a common patch or do you still have differences of approach? >The changes are: > > - Splitting up the kdb_state variable to > decouple data used for inter-processor > synchronization from local flags. Good idea. > - Avoid having an extra layer of nesting > if a processor is already in kdb when the > kdb inter-processor interrupt is delivered. I agree with the aim but am a bit unhappy with putting the code in entry.S. Patching the assembler closes the window between int3 and NMI to a few instructions, at the cost of extra asm. Moving the kdb_in_kdb setting to do_int3 will use C instead of asm. It is a trade off, a slightly larger window for easier to maintain code.
