On Tue, Mar 04, 2003 at 01:50:47PM -0800, Kip Walker wrote: > > Is anyone else interested in having the 64-bit kernel *not* use the CP0 > watchpoint registers for storing the kernel stack pointer for the CPU's > current process? > > I have a couple problems with this: > - there are read-only bits in watchhi (according to the MIPS64 spec) so > hoping to save and restore all high 32 bits (as currently coded) seems > unjustified. > - somebody might want to actually *use* watchpoints (a JTAG debugger, > in my case) > I agree. This is a good thing to do. > I put together something that works, based on the 32-bit kernel which > has an array of kernelsp's instead of keeping it in CP0. Some notes > about this solution are: > - processor id isn't as easy to get in the 64-bit kernel since > CP0_CONTEXT has (&pgd_current[cpu] << 23) instead of (cpu << 23) so in > this patch I use ((&pgd_current[cpu] - &pgd_current[0]) + &kernelsp) > which seems expensive. I can't think of any better way than this. Anybody knows how IRIX does this? Jun
