Re: [BProc] vmadump: mips port; apparenlt bug; etc

[Erik A. H. <er...@he...>]

On Sun, Mar 03, 2002 at 07:30:19PM -0500, Grant Taylor wrote:
> FP doesn't work on this CPU, anyway.  I'd need to make the in-kernel
> fp simulator dump state!

The simulated FPU state should still be in the thread_struct more or
less like a real FPU.

> The flush_icache_range() implementation is sb1_flush_icache_range() in
> arch/mips/mm/sb1.c.  The comments there and in the other flush flavors
> speak of Kseg0 addresses, which is what made me think it expected
> non-userspace addresses.

KSEG0 is address that physical memory is mapped at in the kernel's
virtual address space.  KSEG0 addresses seem to mean "virtual" to me.

I think I said "user" addresses when I meant "virtual" addresses.  All
these flush routines take virtual addresses.  User/kernel space isn't
a meaningful distinction except with respect to trap handling.  That
shouldn't be an issue though.  It's very unlikely that a page won't be
present which flush_icache_range is called since we just got finished
writing to that page.

> Shouldn't calling flush_icache_page() on page table entries should do
> the right thing either way?

Yeah, it should.  Make sure you use the virtual address though.  No
manual page table walking should be required.

> Or even with normal stuff.  GDB disassembles on our target at the rate
> of one instruction every several seconds!

Neato.

> Yes, I got all this working flawlessly on uniprocessor by mangling all
> the entry and exit points to do full saves and restores.  It's ugly
> and inefficient, but until everything actually works this will have to
> do.

Since you don't seem to be porting BProc, would you mind telling me
what the application is?  Embedded something or other?

- Erik
-- 
Erik Arjan Hendriks          Printed On 100 Percent Recycled Electrons
er...@he...                   Contents may settle during shipment