SMP broken on pre-ACPI machine.

DISCUSSION Dave Jones 4 participants 9 messages Oct 18, 2006 – Oct 19, 2006 ACPI

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Dave Jones

author

2006-10-18 22:24 UTC #0 lore raw

I've been chasing a bug that got filed against the Fedora kernel a while back: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=199052
This is a dual pentium pro from an era before we had ACPI, and it seems to be falling foul of this test in smpboot.c ..

    if (!smp_found_config && !acpi_lapic) {
        printk(KERN_NOTICE "SMP motherboard not detected.\n");
        smpboot_clear_io_apic_irqs();
        phys_cpu_present_map = physid_mask_of_physid(0);
        if (APIC_init_uniprocessor())
            printk(KERN_NOTICE "Local APIC not detected."
                       " Using dummy APIC emulation.\n");
        map_cpu_to_logical_apicid();
        cpu_set(0, cpu_sibling_map[0]);
        cpu_set(0, cpu_core_map[0]);
        return;
    }

My initial reaction is that the !acpi_lapic test should be conditional on some variable that gets set if the ACPI parsing actually succeeded.

Thoughts?

Dave

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Sergio Monteiro Basto

2006-10-18 23:45 UTC #1 lore raw

Quoted 19 lines · Dave Jones

I've been chasing a bug that got filed against the Fedora kernel a while back: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=199052
This is a dual pentium pro from an era before we had ACPI, and it seems to be falling foul of this test in smpboot.c ..
    if (!smp_found_config && !acpi_lapic) {
        printk(KERN_NOTICE "SMP motherboard not detected.\n");
        smpboot_clear_io_apic_irqs();
        phys_cpu_present_map = physid_mask_of_physid(0);
        if (APIC_init_uniprocessor())
            printk(KERN_NOTICE "Local APIC not detected."
                       " Using dummy APIC emulation.\n");
        map_cpu_to_logical_apicid();
        cpu_set(0, cpu_sibling_map[0]);
        cpu_set(0, cpu_core_map[0]);
        return;
    }

Quoted 7 lines

My initial reaction is that the !acpi_lapic test should be conditional on some variable that gets set if the ACPI parsing actually succeeded.
Thoughts?
Dave

acpi=off ? this machine should work with APM. BTW, so time ago, this machine would enter in ACPI blacklist (by the year of bios) and ACPI was turned off automatically.

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Sérgio M.B.

Sergio Monteiro Basto

2006-10-18 23:48 UTC #2 lore raw

In reply to Dave Jones

Quoted 19 lines · Dave Jones

I've been chasing a bug that got filed against the Fedora kernel a while back: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=199052
This is a dual pentium pro from an era before we had ACPI, and it seems to be falling foul of this test in smpboot.c ..
    if (!smp_found_config && !acpi_lapic) {
        printk(KERN_NOTICE "SMP motherboard not detected.\n");
        smpboot_clear_io_apic_irqs();
        phys_cpu_present_map = physid_mask_of_physid(0);
        if (APIC_init_uniprocessor())
            printk(KERN_NOTICE "Local APIC not detected."
                       " Using dummy APIC emulation.\n");
        map_cpu_to_logical_apicid();
        cpu_set(0, cpu_sibling_map[0]);
        cpu_set(0, cpu_core_map[0]);
        return;
    }

Quoted 7 lines

My initial reaction is that the !acpi_lapic test should be conditional on some variable that gets set if the ACPI parsing actually succeeded.
Thoughts?
Dave

acpi=off ? this machine should work with APM. BTW, so time ago, this machine would enter in ACPI blacklist (by the year of bios) and ACPI was turned off automatically.

Signature · 1 line

Sérgio M.B.

Dave Jones

author

2006-10-19 03:04 UTC #3 lore raw

Quoted 6 lines · Sergio Monteiro Basto

Quoted 5 lines · Dave Jones
I've been chasing a bug that got filed against the Fedora kernel a while back: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=199052
This is a dual pentium pro from an era before we had ACPI, and it seems to be falling foul of this test in smpboot.c ..

Quoted 7 lines

Quoted 5 lines
    if (!smp_found_config && !acpi_lapic) {
        printk(KERN_NOTICE "SMP motherboard not detected.\n");
My initial reaction is that the !acpi_lapic test should be conditional on some variable that gets set if the ACPI parsing actually succeeded.
acpi=off ?

This is irrelevant. There are no acpi tables, so acpi will disable itself.

Quoted 1 line

this machine should work with APM.

Also irrelevant, as power management isn't the problem here.

Quoted 3 lines

BTW, so time ago, this
machine would enter in ACPI blacklist (by the year of bios) and ACPI was turned off automatically.

Finally, this machine has no DMI tables, so date blacklists are also useless. (Not that it matters anyway due to the lack of ACPI tables)

Dave

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Len Brown

2006-10-19 05:31 UTC #4 lore raw

In reply to Dave Jones

Quoted 19 lines · Dave Jones

I've been chasing a bug that got filed against the Fedora kernel a while back: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=199052
This is a dual pentium pro from an era before we had ACPI, and it seems to be falling foul of this test in smpboot.c ..
    if (!smp_found_config && !acpi_lapic) {
        printk(KERN_NOTICE "SMP motherboard not detected.\n");
        smpboot_clear_io_apic_irqs();
        phys_cpu_present_map = physid_mask_of_physid(0);
        if (APIC_init_uniprocessor())
            printk(KERN_NOTICE "Local APIC not detected."
                       " Using dummy APIC emulation.\n");
        map_cpu_to_logical_apicid();
        cpu_set(0, cpu_sibling_map[0]);
        cpu_set(0, cpu_core_map[0]);
        return;
    }

Quoted 2 lines

My initial reaction is that the !acpi_lapic test should be conditional on some variable that gets set if the ACPI parsing actually succeeded.

acpi_lapic isn't related to the problem at hand -- that smp_found_config is not set.

That said, allowing acpi_lapic=1 to bail out of this check has the sole function of allowing SMP/PIC configurations. (smp_found_config in ACPI mode is set if acpi_lapic and acpi_ioapic are set) SMP/PIC configurations are not very interesting, except for debugging. Indeed, MPS prohibits them by mandating an IOAPIC be present for SMP -- but ACPI has no such rule.

-Len

Dave Jones

author

2006-10-19 19:17 UTC #5 lore raw

Quoted 6 lines · Len Brown

Quoted 5 lines · Dave Jones
I've been chasing a bug that got filed against the Fedora kernel a while back: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=199052
This is a dual pentium pro from an era before we had ACPI, and it seems to be falling foul of this test in smpboot.c ..

Quoted 7 lines

Quoted 5 lines
    if (!smp_found_config && !acpi_lapic) {
        printk(KERN_NOTICE "SMP motherboard not detected.\n");
My initial reaction is that the !acpi_lapic test should be conditional on some variable that gets set if the ACPI parsing actually succeeded.
acpi_lapic isn't related to the problem at hand -- that smp_found_config is not set.

Right, it just seemed odd to me when I was eyeballing this code.

Quoted 6 lines

That said, allowing acpi_lapic=1 to bail out of this check has the sole function of allowing SMP/PIC configurations. (smp_found_config in ACPI mode is set if acpi_lapic and acpi_ioapic are set) SMP/PIC configurations are not very interesting, except for debugging. Indeed, MPS prohibits them by mandating an IOAPIC be present for SMP -- but ACPI has no such rule.

Why smp_found_config isn't set in that guys configuration is a mystery to me, as his MPS tables look sane..

MP Table:
# APIC ID Version State Family Model Step Flags
# 0 0x10 BSP, usable 6 2 1 0x0381
# 0 0x10 AP, usable 6 1 7 0xfbff

Hmm, wait, he has unpaired CPUs. I wonder if that's the reason. I know *some* combinations of PPro's are valid to be paired, but I'll need to dig out the old docs to be sure.

Dave

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Dave Jones

author

2006-10-19 20:11 UTC #6 lore raw

Quoted 11 lines · Dave Jones

Why smp_found_config isn't set in that guys configuration is a mystery to me, as his MPS tables look sane..
MP Table:
# APIC ID Version State Family Model Step Flags
# 0 0x10 BSP, usable 6 2 1 0x0381
# 0 0x10 AP, usable 6 1 7 0xfbff
Hmm, wait, he has unpaired CPUs. I wonder if that's the reason. I know *some* combinations of PPro's are valid to be paired, but I'll need to dig out the old docs to be sure.

Ok, after reading http://www.intel.com/design/archives/processors/pro/docs/242689.htm
I'm more puzzled than ever. There never was a model 2 Pentium Pro. Either this BIOS is on crack and putting nonsense in its MPS tables,
or this is a hardware flaw of some sort.

Dave

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Alan Cox

2006-10-19 22:15 UTC #7 lore raw

Ar Iau, 2006-10-19 am 16:11 -0400, ysgrifennodd Dave Jones:

Quoted 8 lines · Dave Jones

Quoted 7 lines
Why smp_found_config isn't set in that guys configuration is a mystery to me, as his MPS tables look sane..
MP Table:
# APIC ID Version State Family Model Step Flags
# 0 0x10 BSP, usable 6 2 1 0x0381

Isn't that an "overdrive" ? if so it isn't supposed to be SMP capable

Dave Jones

author

2006-10-19 23:21 UTC #8 lore raw

Quoted 11 lines · Alan Cox

Ar Iau, 2006-10-19 am 16:11 -0400, ysgrifennodd Dave Jones:
Quoted 8 lines · Dave Jones
Quoted 7 lines
Why smp_found_config isn't set in that guys configuration is a mystery to me, as his MPS tables look sane..
MP Table:
# APIC ID Version State Family Model Step Flags
# 0 0x10 BSP, usable 6 2 1 0x0381
Isn't that an "overdrive" ? if so it isn't supposed to be SMP capable

I don't think so. The only overdrive that fitted in a socket 8 board was a PPro->PentiumII thing, which would be model 3 stepping 2 as far as I can figure out from a lengthy archeology trip through developer.intel.com.

There were also some Socket8->Socket370 convertors, but afaik they just passed through the family/model/stepping of whatever was plugged into them.

Dave

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