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SubjectRe: [patch 1/1] Do not enforce unique IO_APIC_ID for Xeon processors in EM64T mode (x86_64)
Date
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); -
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--
James Cleverdon
IBM LTC (xSeries Linux Solutions)
{jamesclv(Unix, preferred), cleverdj(Notes)} at us dot ibm dot comm
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