Date: Fri, 8 Sep 2006 14:44:17 -0400 From: John Baldwin <jhb@freebsd.org> To: "Bharath Bhushan" <bharath.bhushan@gmail.com> Cc: freebsd-ia32@freebsd.org Subject: Re: io apic question Message-ID: <200609081444.17428.jhb@freebsd.org> In-Reply-To: <29683db20609081134v3140b663ua376b59041881ed9@mail.gmail.com> References: <29683db20609012326i351eb455ja3b0aade681c7773@mail.gmail.com> <200609051446.36261.jhb@freebsd.org> <29683db20609081134v3140b663ua376b59041881ed9@mail.gmail.com>
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On Friday 08 September 2006 14:34, Bharath Bhushan wrote: > Thanks John. > > Can you please point me to the place where cache-disabled mapping is > being done in 7.0? > I looked at -- ioapic_create -> pmap_mapdev -> pmap_kenter -> > pte_store(pte, pa | PG_RW | PG_V | pgeflag); > > I could not find any references to PG_N in code related to pmap or to IOAPICs. In 7.0 pmap_mapdev() calls pmap_mapdev_attr(..., PAT_UNCACHEABLE). > On 9/6/06, John Baldwin <jhb@freebsd.org> wrote: > > On Saturday 02 September 2006 02:26, Bharath Bhushan wrote: > > > I am looking at 4.9 sources. > > > > > > When the local apic is mapped into SMPpt in > > > sys/i386/i386/pmap.c:pmap_bootstrap(), it is mapped cache-disabled > > > (PG_N). > > > > > > When the IO apics are being mapped into SMPpt in > > > sys/i386/i386/mp_machdep.c:mptable_pass2(), it is *not* mapped > > > cache-disabled. > > > > > > Why is this difference? > > > > Probably a bug. > > > > > In 5.5, I see that ioapic_create() calls pmap_createdev(), which > > > allocates cache-enabled kind of mapping. > > > > > > Am I missing something here? > > > > In 7.0 we map them cache-disabled now. > > > > -- > > John Baldwin > > > > > -- > Thanks > Bharath > -- John Baldwin
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