Date: Mon, 08 Jul 2002 13:52:48 -0700 From: Peter Wemm <peter@wemm.org> To: John Baldwin <jhb@FreeBSD.org> Cc: current@freebsd.org Subject: Re: Remember my ill-fated i386 smp pmap optimizations? Message-ID: <20020708205248.6D4EC3808@overcee.wemm.org> In-Reply-To: <XFMail.20020708152756.jhb@FreeBSD.org>
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John Baldwin wrote:
>
> On 08-Jul-2002 Peter Wemm wrote:
> > A few months ago, I had a bit of a disaster with some pmap optimizations.
> > After committing, all hell broke loose. It was backed out completely.
> >
> > I finally found the problem (diff cleaned up to highlight the problem):
> >
> > pmap_mapdev()
> > ...
> > for (tmpva = va; size > 0; ) {
> > pte = vtopte(tmpva);
> > *pte = pa | PG_RW | PG_V | pgeflag;
> > size -= PAGE_SIZE;
> > tmpva += PAGE_SIZE;
> > - pa += PAGE_SIZE;
> > }
> > invltlb();
> >
> > Excuse me while I go outside and shoot myself.
>
> Hahahaha!
>
> Glad to see you have fixed them. :)
Unfortunately, there are still more problems. :-(
I have found some of them. And what is really scary is that I have
verified that some of what Terry has been FUD'ing(*) about for our TLB
(mis)management is actually correct. :-( We have code that simply will not
work (ie: vm86 will explode when doing VESA calls) if certain accidental
conditions that mask the bugs no longer occur.
I've still got to find this one though:
TPTE at 0xbfca01f0 IS ZERO @ VA 2807c000
panic: bad peter
db> trace
panic(c043087f,bfca01f0,2807c000,1,c040e9d7) at panic+0x84
pmap_remove_pages(c15d6ed0,0,bfc00000,115,c028aee0) at pmap_remove_pages+0x9c
exit1(c15d5180,8b,c6,c24a0d04,0) at exit1+0x4f0
sigexit(c15d5180,b,c040fbb1,6e9,0) at sigexit+0x1b9
postsig(b,0,c0413100,e4,400) at postsig+0x11b
ast(d3aa5d48) at ast+0x328
doreti_ast() at doreti_ast+0x1a
This also happens from a plain exit() syscall.
Cheers,
-Peter
--
Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5
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