Date: Wed, 24 May 2000 10:45:33 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Martin Cracauer <cracauer@cons.org> Cc: Peter Wemm <peter@FreeBSD.ORG>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/i386/i386 mem.c Message-ID: <200005241745.KAA76140@apollo.backplane.com> References: <200005241422.HAA63818@freefall.freebsd.org> <20000524194159.A74787@cons.org>
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:> pmap_enter() masked off the page offset bits, pmap_kenter() did not.
:> This (I believe) is the cause of the XFree86 startup and/or mptable(8)
:> panics when programs were reading from /dev/mem at non-page-aligned
:> offsets. The offsets were being converted into random page flags in the
:> page tables. :-( (including PG_PS = 4MB page size)
:
:Fixed it for me.
:
:Thanks!
: Martin
As a side note, the problem is one of design. The original design, that
is. The pmap code has traditionally treated physical addresses and
page table entry fields interchangeably which means that it is very easy
to make a coding mistake when cleaning things up... and to miss the
mistake when reviewing :-)
-Matt
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