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Date: Sun, 30 Mar 2008 18:33:04 -0700
From: "Yinghai Lu" <yhlu.kernel@...il.com>
To: "Jack Steiner" <steiner@....com>,
"Andi Kleen" <andi@...stfloor.org>
Cc: mingo@...e.hu, tglx@...utronix.de, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/8] x86_64: Support for new UV apic
On Sun, Mar 30, 2008 at 4:22 PM, Yinghai Lu <yhlu.kernel@...il.com> wrote:
>
> On Fri, Mar 28, 2008 at 12:12 PM, Jack Steiner <steiner@....com> wrote:
> >
> > UV supports really big systems. So big, in fact, that the APICID register
> > does not contain enough bits to contain an APICID that is unique across all
> > cpus.
> >
> > The UV BIOS supports 3 APICID modes:
> >
> > - legacy mode. This mode uses the old APIC mode where
> > APICID is in bits [31:24] of the APICID register.
> >
> > - x2apic mode. This mode is whitebox-compatible. APICIDs
> > are unique across all cpus. Standard x2apic APIC operations
> > (Intel-defined) can be used for IPIs. The node identifier
> > fits within the Intel-defined portion of the APICID register.
> >
> > - x2apic-uv mode. In this mode, the APICIDs on each node have
> > unique IDs, but IDs on different node are not unique. For example,
> > if each mode has 32 cpus, the APICIDs on each node might be
> > 0 - 31. Every node has the same set of IDs.
> > The UV hub is used to route IPIs/interrupts to the correct node.
> > Traditional APIC operations WILL NOT WORK.
> >
> > In x2apic-uv mode, the ACPI tables all contain a full unique ID (note:
> > exact bit layout still changing but the following is close):
> >
> > nnnnnnnnnnlc0cch
> > n = unique node number
> > l = socket number on board
> > c = core
> > h = hyperthread
> >
> > Only the "lc0cch" bits are written to the APICID register. The remaining bits are
> > supplied by having the get_apic_id() function "OR" the extra bits into the value
> > read from the APICID register. (Hmmm.. why not keep the ENTIRE APICID register
> > in per-cpu data....)
> >
> > The x2apic-uv mode is recognized by the MADT table containing:
> > oem_id = "SGI"
> > oem_table_id = "UV-X"
> >
> > Based on:
> > git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86.git
> >
> > Signed-off-by: Jack Steiner <steiner@....com>
> >
> > ---
> > arch/x86/kernel/Makefile | 2
> > arch/x86/kernel/apic_64.c | 2
> > arch/x86/kernel/genapic_64.c | 18 ++
> > arch/x86/kernel/genx2apic_uv_x.c | 245 +++++++++++++++++++++++++++++++++++++++
> > arch/x86/kernel/setup64.c | 4
> > arch/x86/kernel/smpboot.c | 5
> > include/asm-x86/genapic_64.h | 5
> > include/asm-x86/smp.h | 5
> > 8 files changed, 285 insertions(+), 1 deletion(-)
> >
> > Index: linux/arch/x86/kernel/genapic_64.c
> > ===================================================================
> > --- linux.orig/arch/x86/kernel/genapic_64.c 2008-03-28 13:06:07.000000000 -0500
> > +++ linux/arch/x86/kernel/genapic_64.c 2008-03-28 13:06:12.000000000 -0500
> > @@ -15,6 +15,7 @@
> > #include <linux/kernel.h>
> > #include <linux/ctype.h>
> > #include <linux/init.h>
> > +#include <linux/hardirq.h>
> >
> > #include <asm/smp.h>
> > #include <asm/ipi.h>
> > @@ -32,6 +33,7 @@ void *x86_cpu_to_apicid_early_ptr;
> > #endif
> > DEFINE_PER_CPU(u16, x86_cpu_to_apicid) = BAD_APICID;
> > EXPORT_PER_CPU_SYMBOL(x86_cpu_to_apicid);
> > +DEFINE_PER_CPU(int, x2apic_extra_bits);
> >
> > struct genapic __read_mostly *genapic = &apic_flat;
> >
> > @@ -42,6 +44,9 @@ static enum uv_system_type uv_system_typ
> > */
> > void __init setup_apic_routing(void)
> > {
> > + if (uv_system_type == UV_NON_UNIQUE_APIC)
> > + genapic = &apic_x2apic_uv_x;
> > + else
> > #ifdef CONFIG_ACPI
> > /*
> > * Quirk: some x86_64 machines can only use physical APIC mode
> > @@ -82,6 +87,19 @@ int __init acpi_madt_oem_check(char *oem
> > return 0;
> > }
> >
> > +unsigned int read_apic_id(void)
> > +{
> > + unsigned int id;
> > +
> > + WARN_ON(preemptible());
> > + id = apic_read(APIC_ID);
> > + if (uv_system_type >= UV_X2APIC)
> > + id |= __get_cpu_var(x2apic_extra_bits);
> > + else
> > + id = (id >> 24) & 0xFFu;;
> > + return id;
> > +}
>
> so this is "the new one of Friday"?
>
> it still wrong. you can not shit id here. ot broke all x86_64 smp.
>
> Did you test it on non UV_X2APIC box?
anyway the read_apic_id is totally wrong, even for your UV_X2APIC box.
because id=apic_read(APIC_ID) will have apic_id at bits [31,24], and
id |= __get_cpu_var(x2apic_extra_bits) is assuming that is on bits [5,0]
so you even didn't test in your UV_X2APIC box!
YH
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