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SubjectRE: [patch 1/1] Do not enforce unique IO_APIC_ID for Xeon processors in EM64T mode (x86_64)
Date
From
I tried the following patch:

--- io_apic.c.orig 2005-05-11 03:42:40.000000000 -0400
+++ io_apic.c 2005-05-11 03:44:28.000000000 -0400
@@ -2427,12 +2427,13 @@ int __init io_apic_get_unique_id (int io
physid_mask_t tmp;
unsigned long flags;
int i = 0;
+ static int no_ioapic_check;

/* Don't check I/O APIC IDs for some xAPIC systems. They have
* no meaning without the serial APIC bus.
*/

- if (NO_IOAPIC_CHECK)
+ if (no_ioapic_check)
return apic_id;

/*
@@ -2449,6 +2450,13 @@ int __init io_apic_get_unique_id (int io
reg_00.raw = io_apic_read(ioapic, 0);
spin_unlock_irqrestore(&ioapic_lock, flags);

+ if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) &&
+ (boot_cpu_data.x86 == 15)) {
+ if (reg_00.bits.delivery_type)
+ no_ioapic_check = 1;
+ return apic_id;
+ }
+
if (apic_id >= get_physical_broadcast()) {
printk(KERN_WARNING "IOAPIC[%d]: Invalid apic_id %d,
trying "
"%d\n", ioapic, apic_id, reg_00.bits.ID);

To my surprise, it didn't work, and when I dumped the I/O APIC registers
it turned out that on ES7000 the parallel delivery bit wasn't set!

<7>.... register #00: A4000000
<7>....... : physical APIC id: A4
<7>....... : Delivery Type: 0
<7>....... : LTS : 0
<7>.... register #01: 00170004
<7>....... : max redirection entries: 0017
<7>....... : PRQ implemented: 0
<7>....... : IO APIC version: 0004
Version number was not 0x11 as James mentioned, it was 4, and I couldn't
find anything documented on the I/O xAPIC versioning.

Looks like the need in the unique id can only be keyed of the local APIC
id, and probably it is a good idea to keep the NO_IOAPIC_CHECK for
subarchs that can override the heuristics?

Thanks,
--Natalie

> -----Original Message-----
> From: James Cleverdon [mailto:jamesclv@us.ibm.com]
> Sent: Monday, May 09, 2005 1:16 PM
> To: Andi Kleen
> Cc: Protasevich, Natalie; akpm@osdl.org;
> zwane@arm.linux.org.uk; len.brown@intel.com;
> venkatesh.pallipadi@intel.com; linux-kernel@vger.kernel.org
> Subject: Re: [patch 1/1] Do not enforce unique IO_APIC_ID for
> Xeon processors in EM64T mode (x86_64)
>
> When I looked earlier, I couldn't find the pins for serial
> APIC bus on Opterons and P4 Xeons with EM64T. So, you should
> be able to safely remove the unique I/O APIC check from x86-64.
>
> For i386, something like this might do:
>
> if (cpu is >= P4 && IOAPIC version >= 0x11 && num_IOAPIC > 0
> && first IOAPIC has parallel mode bit set)
> disable unique check
> else
> enable
>
>
> On Sunday 08 May 2005 06:49 am, Andi Kleen wrote:
> > On Sun, May 08, 2005 at 12:01:22AM -0500, Protasevich,
> Natalie wrote:
> > > > > This patch disables unique IO_APIC_ID check for xAPIC
> > > >
> > > > systems running in EM64T mode. Xeon-based ES7000s panic
> > > > failing this unnecessary check. I added IOAPIC_ID_CHECK
> > > > config option and turned it off for Intel processors. Also
> > > > added the boot option that overrides default and turnes this
> > > > check on/off in case it is needed for some reason. Hope this
> > > > is acceptable way to fix the problem.
> > > >
> > > > I think we can turn it off for all x86-64 systems. Near all
> > > > EM64T systems have xAPIC. AMD processors don't need it
> > > > neither. That would only leave the new IBM summit2 chipset,
> > > > but I suppose they also don't need this (James please
> > > > complain if I am wrong)
> > > > So can you please do a new patch that just removes this code?
> > >
> > > Sure, I will remove the io_apic_get_unique_id() then. Perhaps, it
> > > will be easy to put it back in if someone implements a
> chipset that
> > > needs it.
> >
> > I did it myself now.
> >
> > > Andi, I submitted the patch for i386 a little while ago
> > > http://www.ussg.iu.edu/hypermail/linux/kernel/0505.0/0195.html (I
> > > sent it to you also, but just noticed that it was not your usual
> > > email address - where did I get if from? have no idea...) Genapic
> > > in i386 has a NO_IOAPIC_CHECK flag that is defined in every
> > > subarch, so it was easy to fix the problem by making use of it in
> > > ACPI boot path just as it was used in MP path.
> >
> > That will not help on the other systems who don't have an own
> > subarchitecture but still run into problems with the check.
> >
> > I think the right strategy for i386 would be to remove this check
> > thing from the subarchitecture and implement the heuristic described
> > in the last mail.
> >
> > -Andi
> >
> >
> > Remove unique APIC/IO-APIC ID check
> >
> > It is unnecessary on modern Intel or AMD systems, and that
> > is all we support on x86-64
> >
> > Also causes problems on various systems
> >
> > Signed-off-by: Andi Kleen <ak@suse.de>
> >
> > Index: linux/arch/x86_64/kernel/io_apic.c
> > ===================================================================
> > --- linux.orig/arch/x86_64/kernel/io_apic.c
> > +++ linux/arch/x86_64/kernel/io_apic.c
> > @@ -1805,76 +1805,6 @@ device_initcall(ioapic_init_sysfs);
> >
> > #define IO_APIC_MAX_ID 0xFE
> >
> > -int __init io_apic_get_unique_id (int ioapic, int apic_id)
> > -{
> > - union IO_APIC_reg_00 reg_00;
> > - static physid_mask_t apic_id_map;
> > - unsigned long flags;
> > - int i = 0;
> > -
> > - /*
> > - * The P4 platform supports up to 256 APIC IDs on two
> separate APIC
> > - * buses (one for LAPICs, one for IOAPICs), where
> predecessors only
> > - * supports up to 16 on one shared APIC bus.
> > - *
> > - * TBD: Expand LAPIC/IOAPIC support on P4-class systems to take
> > full - * advantage of new APIC bus architecture.
> > - */
> > -
> > - if (physids_empty(apic_id_map))
> > - apic_id_map = phys_cpu_present_map;
> > -
> > - spin_lock_irqsave(&ioapic_lock, flags);
> > - reg_00.raw = io_apic_read(ioapic, 0);
> > - spin_unlock_irqrestore(&ioapic_lock, flags);
> > -
> > - if (apic_id >= IO_APIC_MAX_ID) {
> > - apic_printk(APIC_QUIET, KERN_WARNING
> "IOAPIC[%d]: Invalid apic_id
> > %d, trying " - "%d\n", ioapic,
> apic_id, reg_00.bits.ID);
> > - apic_id = reg_00.bits.ID;
> > - }
> > -
> > - /*
> > - * Every APIC in a system must have a unique ID or we
> get lots of
> > nice - * 'stuck on smp_invalidate_needed IPI wait' messages.
> > - */
> > - if (physid_isset(apic_id, apic_id_map)) {
> > -
> > - for (i = 0; i < IO_APIC_MAX_ID; i++) {
> > - if (!physid_isset(i, apic_id_map))
> > - break;
> > - }
> > -
> > - if (i == IO_APIC_MAX_ID)
> > - panic("Max apic_id exceeded!\n");
> > -
> > - apic_printk(APIC_VERBOSE, KERN_WARNING
> "IOAPIC[%d]: apic_id %d
> > already used, " - "trying %d\n", ioapic,
> apic_id, i);
> > -
> > - apic_id = i;
> > - }
> > -
> > - physid_set(apic_id, apic_id_map);
> > -
> > - if (reg_00.bits.ID != apic_id) {
> > - reg_00.bits.ID = apic_id;
> > -
> > - spin_lock_irqsave(&ioapic_lock, flags);
> > - io_apic_write(ioapic, 0, reg_00.raw);
> > - reg_00.raw = io_apic_read(ioapic, 0);
> > - spin_unlock_irqrestore(&ioapic_lock, flags);
> > -
> > - /* Sanity check */
> > - if (reg_00.bits.ID != apic_id)
> > - panic("IOAPIC[%d]: Unable change
> apic_id!\n", ioapic);
> > - }
> > -
> > - apic_printk(APIC_VERBOSE,KERN_INFO "IOAPIC[%d]: Assigned apic_id
> > %d\n", ioapic, apic_id); -
> > - return apic_id;
> > -}
> > -
> > -
> > int __init io_apic_get_version (int ioapic)
> > {
> > union IO_APIC_reg_01 reg_01;
> > Index: linux/arch/x86_64/kernel/mpparse.c
> > ===================================================================
> > --- linux.orig/arch/x86_64/kernel/mpparse.c
> > +++ linux/arch/x86_64/kernel/mpparse.c
> > @@ -763,7 +763,7 @@ void __init mp_register_ioapic (
> > mp_ioapics[idx].mpc_apicaddr = address;
> >
> > set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address);
> > - mp_ioapics[idx].mpc_apicid = io_apic_get_unique_id(idx, id);
> > + mp_ioapics[idx].mpc_apicid = id;
> > mp_ioapics[idx].mpc_apicver = io_apic_get_version(idx);
> >
> > /*
> > Index: linux/include/asm-x86_64/io_apic.h
> > ===================================================================
> > --- linux.orig/include/asm-x86_64/io_apic.h
> > +++ linux/include/asm-x86_64/io_apic.h
> > @@ -202,7 +202,6 @@ extern int skip_ioapic_setup;
> > #define io_apic_assign_pci_irqs (mp_irq_entries &&
> > !skip_ioapic_setup && io_apic_irqs)
> >
> > #ifdef CONFIG_ACPI_BOOT
> > -extern int io_apic_get_unique_id (int ioapic, int apic_id);
> > extern int io_apic_get_version (int ioapic);
> > extern int io_apic_get_redir_entries (int ioapic);
> > extern int io_apic_set_pci_routing (int ioapic, int pin, int irq,
> > int, int); -
> > To unsubscribe from this list: send the line "unsubscribe
> > linux-kernel" in the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at http://www.tux.org/lkml/
>
> --
> James Cleverdon
> IBM LTC (xSeries Linux Solutions)
> {jamesclv(Unix, preferred), cleverdj(Notes)} at us dot ibm dot comm
>
-
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