Re: [PATCH] irq: add quirk for broken interrupt remapping on 55XX chipsets
On Fri, Mar 1, 2013 at 9:17 AM, Neil Horman wrote:
> A few years back intel published a spec update:
> http://www.intel.com/content/dam/doc/specification-update/5520-and-5500-chipset-ioh-specification-update.pdf
>
> For the 5520 and 5500 chipsets which contained an errata (specificially errata
> 53), which noted that these chipsets can't properly do interrupt remapping,
> and
> as a result the recommend that interrupt remapping be disabled in bios. While
> many vendors have a bios update to do exactly that, not all do, and of course
> not all users update their bios to a level that corrects the problem. As a
> result, occasionally interrupts can arrive at a cpu even after affinity for
> that
> interrupt has be moved, leading to lost or spurrious interrupts (usually
> characterized by the message:
> kernel: do_IRQ: 7.71 No irq handler for vector (irq -1)
>
> There have been several incidents recently of people seeing this error, and
> investigation has shown that they have system for which their BIOS level is
> such
> that this feature was not properly turned off. As such, it would be good to
> give them a reminder that their systems are vulnurable to this problem.
>
> Signed-off-by: Neil Horman
> CC: Prarit Bhargava
> CC: Don Zickus
> CC: Don Dutile
> CC: Bjorn Helgaas
> CC: Asit Mallick
> CC: linux-...@vger.kernel.org
> ---
> drivers/iommu/intel_irq_remapping.c | 20
> include/linux/pci_ids.h | 2 ++
> 2 files changed, 22 insertions(+)
>
> diff --git a/drivers/iommu/intel_irq_remapping.c
> b/drivers/iommu/intel_irq_remapping.c
> index f3b8f23..9bfb6c2 100644
> --- a/drivers/iommu/intel_irq_remapping.c
> +++ b/drivers/iommu/intel_irq_remapping.c
> @@ -1113,3 +1113,23 @@ struct irq_remap_ops intel_irq_remap_ops = {
> .msi_setup_irq = intel_msi_setup_irq,
> .setup_hpet_msi = intel_setup_hpet_msi,
> };
> +
> +
> +static void intel_remapping_check(struct pci_dev *dev)
> +{
> + u8 revision;
> +
> + pci_read_config_byte(dev, PCI_REVISION_ID, &revision);
> +
> + if ((revision == 0x13) && irq_remapping_enabled) {
> + pr_warn("WARNING WARNING WARNING WARNING WARNING WARNING\n"
> + "This system BIOS has enabled interrupt remapping\n"
> + "on a chipset that contains an errata making that\n"
> + "feature unstable. Please reboot with nointremap\n"
> + "added to the kernel command line and contact\n"
> + "your BIOS vendor for an update");
> + }
> +}
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_5520_IOHUB,
> intel_remapping_check);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_5500_IOHUB,
> intel_remapping_check);
only for x86 platform?
If so, you can check that in arch/x86/kernel/early-quirks.c::early_quirks()
and set one flag and later print warning and skip there if someone
need to enable intr-remap.
So users will not need to reboot the system...
Thanks
Yinghai
> +
> diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
> index 31717bd..54027a6 100644
> --- a/include/linux/pci_ids.h
> +++ b/include/linux/pci_ids.h
> @@ -2732,6 +2732,8 @@
> #define PCI_DEVICE_ID_INTEL_LYNNFIELD_MC_CH2_RANK_REV2 0x2db2
> #define PCI_DEVICE_ID_INTEL_LYNNFIELD_MC_CH2_TC_REV20x2db3
> #define PCI_DEVICE_ID_INTEL_82855PM_HB 0x3340
> +#define PCI_DEVICE_ID_INTEL_5500_IOHUB 0x3403
> +#define PCI_DEVICE_ID_INTEL_5520_IOHUB 0x3406
> #define PCI_DEVICE_ID_INTEL_IOAT_TBG4 0x3429
> #define PCI_DEVICE_ID_INTEL_IOAT_TBG5 0x342a
> #define PCI_DEVICE_ID_INTEL_IOAT_TBG6 0x342b
> --
> 1.7.11.7
>
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Re: [PATCH] irq: add quirk for broken interrupt remapping on 55XX chipsets
On Fri, Mar 01, 2013 at 10:20:35AM -0800, Yinghai Lu wrote:
> On Fri, Mar 1, 2013 at 9:17 AM, Neil Horman wrote:
> > A few years back intel published a spec update:
> > http://www.intel.com/content/dam/doc/specification-update/5520-and-5500-chipset-ioh-specification-update.pdf
> >
> > For the 5520 and 5500 chipsets which contained an errata (specificially
> > errata
> > 53), which noted that these chipsets can't properly do interrupt remapping,
> > and
> > as a result the recommend that interrupt remapping be disabled in bios.
> > While
> > many vendors have a bios update to do exactly that, not all do, and of
> > course
> > not all users update their bios to a level that corrects the problem. As a
> > result, occasionally interrupts can arrive at a cpu even after affinity for
> > that
> > interrupt has be moved, leading to lost or spurrious interrupts (usually
> > characterized by the message:
> > kernel: do_IRQ: 7.71 No irq handler for vector (irq -1)
> >
> > There have been several incidents recently of people seeing this error, and
> > investigation has shown that they have system for which their BIOS level is
> > such
> > that this feature was not properly turned off. As such, it would be good to
> > give them a reminder that their systems are vulnurable to this problem.
> >
> > Signed-off-by: Neil Horman
> > CC: Prarit Bhargava
> > CC: Don Zickus
> > CC: Don Dutile
> > CC: Bjorn Helgaas
> > CC: Asit Mallick
> > CC: linux-...@vger.kernel.org
> > ---
> > drivers/iommu/intel_irq_remapping.c | 20
> > include/linux/pci_ids.h | 2 ++
> > 2 files changed, 22 insertions(+)
> >
> > diff --git a/drivers/iommu/intel_irq_remapping.c
> > b/drivers/iommu/intel_irq_remapping.c
> > index f3b8f23..9bfb6c2 100644
> > --- a/drivers/iommu/intel_irq_remapping.c
> > +++ b/drivers/iommu/intel_irq_remapping.c
> > @@ -1113,3 +1113,23 @@ struct irq_remap_ops intel_irq_remap_ops = {
> > .msi_setup_irq = intel_msi_setup_irq,
> > .setup_hpet_msi = intel_setup_hpet_msi,
> > };
> > +
> > +
> > +static void intel_remapping_check(struct pci_dev *dev)
> > +{
> > + u8 revision;
> > +
> > + pci_read_config_byte(dev, PCI_REVISION_ID, &revision);
> > +
> > + if ((revision == 0x13) && irq_remapping_enabled) {
> > + pr_warn("WARNING WARNING WARNING WARNING WARNING WARNING\n"
> > + "This system BIOS has enabled interrupt remapping\n"
> > + "on a chipset that contains an errata making that\n"
> > + "feature unstable. Please reboot with nointremap\n"
> > + "added to the kernel command line and contact\n"
> > + "your BIOS vendor for an update");
> > + }
> > +}
> > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL,
> > PCI_DEVICE_ID_INTEL_5520_IOHUB, intel_remapping_check);
> > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL,
> > PCI_DEVICE_ID_INTEL_5500_IOHUB, intel_remapping_check);
>
> only for x86 platform?
> If so, you can check that in arch/x86/kernel/early-quirks.c::early_quirks()
> and set one flag and later print warning and skip there if someone
> need to enable intr-remap.
> So users will not need to reboot the system...
>
> Thanks
>
I was under the impression that BIOS might have enabled irq remapping prior to
the OS booting, at which point a reboot was requried anyway.
Neil
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Re: [PATCH] irq: add quirk for broken interrupt remapping on 55XX chipsets
On 03/02/2013 02:20 AM, Yinghai Lu wrote:
> On Fri, Mar 1, 2013 at 9:17 AM, Neil Horman wrote:
>> A few years back intel published a spec update:
>> http://www.intel.com/content/dam/doc/specification-update/5520-and-5500-chipset-ioh-specification-update.pdf
>>
>> For the 5520 and 5500 chipsets which contained an errata (specificially
>> errata
>> 53), which noted that these chipsets can't properly do interrupt remapping,
>> and
>> as a result the recommend that interrupt remapping be disabled in bios.
>> While
>> many vendors have a bios update to do exactly that, not all do, and of course
>> not all users update their bios to a level that corrects the problem. As a
>> result, occasionally interrupts can arrive at a cpu even after affinity for
>> that
>> interrupt has be moved, leading to lost or spurrious interrupts (usually
>> characterized by the message:
>> kernel: do_IRQ: 7.71 No irq handler for vector (irq -1)
>>
>> There have been several incidents recently of people seeing this error, and
>> investigation has shown that they have system for which their BIOS level is
>> such
>> that this feature was not properly turned off. As such, it would be good to
>> give them a reminder that their systems are vulnurable to this problem.
>>
>> Signed-off-by: Neil Horman
>> CC: Prarit Bhargava
>> CC: Don Zickus
>> CC: Don Dutile
>> CC: Bjorn Helgaas
>> CC: Asit Mallick
>> CC: linux-...@vger.kernel.org
>> ---
>> drivers/iommu/intel_irq_remapping.c | 20
>> include/linux/pci_ids.h | 2 ++
>> 2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/iommu/intel_irq_remapping.c
>> b/drivers/iommu/intel_irq_remapping.c
>> index f3b8f23..9bfb6c2 100644
>> --- a/drivers/iommu/intel_irq_remapping.c
>> +++ b/drivers/iommu/intel_irq_remapping.c
>> @@ -1113,3 +1113,23 @@ struct irq_remap_ops intel_irq_remap_ops = {
>> .msi_setup_irq = intel_msi_setup_irq,
>> .setup_hpet_msi = intel_setup_hpet_msi,
>> };
>> +
>> +
>> +static void intel_remapping_check(struct pci_dev *dev)
>> +{
>> + u8 revision;
>> +
>> + pci_read_config_byte(dev, PCI_REVISION_ID, &revision);
>> +
>> + if ((revision == 0x13) && irq_remapping_enabled) {
>> + pr_warn("WARNING WARNING WARNING WARNING WARNING WARNING\n"
>> + "This system BIOS has enabled interrupt remapping\n"
>> + "on a chipset that contains an errata making that\n"
>> + "feature unstable. Please reboot with nointremap\n"
>> + "added to the kernel command line and contact\n"
>> + "your BIOS vendor for an update");
>> + }
>> +}
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL,
>> PCI_DEVICE_ID_INTEL_5520_IOHUB, intel_remapping_check);
>> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL,
>> PCI_DEVICE_ID_INTEL_5500_IOHUB, intel_remapping_check);
>
> only for x86 platform?
> If so, you can check that in arch/x86/kernel/early-quirks.c::early_quirks()
> and set one flag and later print warning and skip there if someone
> need to enable intr-remap.
> So users will not need to reboot the system...
We have just struggled with this issue when doing kvm restarting stress tests,
and finally found it's a chipset errata. Thanks for fix it.
And I think 5520/5500 is for x86 only, so could move it to x86 arch
subdirectory.
Regards!
Gerry
>
> Thanks
>
> Yinghai
>
>> +
>> diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
>> index 31717bd..54027a6 100644
>> --- a/include/linux/pci_ids.h
>> +++ b/include/linux/pci_ids.h
>> @@ -2732,6 +2732,8 @@
>> #define PCI_DEVICE_ID_INTEL_LYNNFIELD_MC_CH2_RANK_REV2 0x2db2
>> #define PCI_DEVICE_ID_INTEL_LYNNFIELD_MC_CH2_TC_REV20x2db3
>> #define PCI_DEVICE_ID_INTEL_82855PM_HB 0x3340
>> +#define PCI_DEVICE_ID_INTEL_5500_IOHUB 0x3403
>> +#define PCI_DEVICE_ID_INTEL_5520_IOHUB 0x3406
>> #define PCI_DEVICE_ID_INTEL_IOAT_TBG4 0x3429
>> #define PCI_DEVICE_ID_INTEL_IOAT_TBG5 0x342a
>> #define PCI_DEVICE_ID_INTEL_IOAT_TBG6 0x342b
>> --
>> 1.7.11.7
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>> the body of a message to majord...@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
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Re: [PATCH] irq: add quirk for broken interrupt remapping on 55XX chipsets
Hi,
> if ((revision == 0x13) && irq_remapping_enabled) {
> + pr_warn("WARNING WARNING WARNING WARNING WARNING
> WARNING\n"
> + "This system BIOS has enabled interrupt
> remapping\n"
> + "on a chipset that contains an errata making
> that\n"
> + "feature unstable. Please reboot with
> nointremap\n"
> + "added to the kernel command line and contact\n"
> + "your BIOS vendor for an update");
> + }
Forgive me, but ISTR that there's a special BIOS firmware quirk bug annotating
logger warning message mechanism (have I managed to hit all keywords yet? ;)
in the kernel which might be useful in this case.
OK, found something (but I don't think it was the mechanism
that ISTR - perhaps it got modernized?):
include/linux/printk.h:
/*
* FW_BUG
* Add this to a message where you are sure the firmware is buggy or
* behaves
* really stupid or out of spec. Be aware that the responsible BIOS
* developer
* should be able to fix this issue or at least get a concrete idea of
* the
* problem by reading your message without the need of looking at the
* kernel
* code.
*
* Use it for definite and high priority BIOS bugs.
*
* FW_WARN
* Use it for not that clear (e.g. could the kernel messed up things
* already?)
* and medium priority BIOS bugs.
*
* FW_INFO
* Use this one if you want to tell the user or vendor about something
* suspicious, but generally harmless related to the firmware.
*
* Use it for information or very low priority BIOS bugs.
*/
So perhaps it is appropriate to be used here.
HTH,
Andreas Mohr
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Re: [PATCH] irq: add quirk for broken interrupt remapping on 55XX chipsets
On 03/01/2013 12:17 PM, Neil Horman wrote:
> A few years back intel published a spec update:
> http://www.intel.com/content/dam/doc/specification-update/5520-and-5500-chipset-ioh-specification-update.pdf
>
> For the 5520 and 5500 chipsets which contained an errata (specificially errata
> 53), which noted that these chipsets can't properly do interrupt remapping,
> and
> as a result the recommend that interrupt remapping be disabled in bios. While
> many vendors have a bios update to do exactly that, not all do, and of course
> not all users update their bios to a level that corrects the problem. As a
> result, occasionally interrupts can arrive at a cpu even after affinity for
> that
> interrupt has be moved, leading to lost or spurrious interrupts (usually
> characterized by the message:
> kernel: do_IRQ: 7.71 No irq handler for vector (irq -1)
>
> There have been several incidents recently of people seeing this error, and
> investigation has shown that they have system for which their BIOS level is
> such
> that this feature was not properly turned off. As such, it would be good to
> give them a reminder that their systems are vulnurable to this problem.
>
> Signed-off-by: Neil Horman
> CC: Prarit Bhargava
> CC: Don Zickus
> CC: Don Dutile
> CC: Bjorn Helgaas
> CC: Asit Mallick
> CC: linux-...@vger.kernel.org
> ---
> drivers/iommu/intel_irq_remapping.c | 20
> include/linux/pci_ids.h | 2 ++
> 2 files changed, 22 insertions(+)
>
> diff --git a/drivers/iommu/intel_irq_remapping.c
> b/drivers/iommu/intel_irq_remapping.c
> index f3b8f23..9bfb6c2 100644
> --- a/drivers/iommu/intel_irq_remapping.c
> +++ b/drivers/iommu/intel_irq_remapping.c
> @@ -1113,3 +1113,23 @@ struct irq_remap_ops intel_irq_remap_ops = {
> .msi_setup_irq = intel_msi_setup_irq,
> .setup_hpet_msi = intel_setup_hpet_msi,
> };
> +
> +
> +static void intel_remapping_check(struct pci_dev *dev)
> +{
> + u8 revision;
> +
> + pci_read_config_byte(dev, PCI_REVISION_ID, &revision);
> +
> + if ((revision == 0x13) && irq_remapping_enabled) {
> + pr_warn("WARNING WARNING WARNING WARNING WARNING WARNING\n"
> + "This system BIOS has enabled interrupt remapping\n"
> + "on a chipset that contains an errata making that\n"
> + "feature unstable. Please reboot with nointremap\n"
> + "added to the kernel command line and contact\n"
> + "your BIOS vendor for an update");
Make this one line? Might be too long but I believe the preferred policy is now
to keep the output on one line so that it is easy to find in the kernel source.
Also, IMO, remove the WARNING WARNING stuff.
You also should probably use HW_ERR here too.
P.
> + }
> +}
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_5520_IOHUB,
> intel_remapping_check);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_5500_IOHUB,
> intel_remapping_check);
> +
> diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
> index 31717bd..54027a6 100644
> --- a/include/linux/pci_ids.h
> +++ b/include/linux/pci_ids.h
> @@ -2732,6 +2732,8 @@
> #define PCI_DEVICE_ID_INTEL_LYNNFIELD_MC_CH2_RANK_REV2 0x2db2
> #define PCI_DEVICE_ID_INTEL_LYNNFIELD_MC_CH2_TC_REV20x2db3
> #define PCI_DEVICE_ID_INTEL_82855PM_HB 0x3340
> +#define PCI_DEVICE_ID_INTEL_5500_IOHUB 0x3403
> +#define PCI_DEVICE_ID_INTEL_5520_IOHUB 0x3406
> #define PCI_DEVICE_ID_INTEL_IOAT_TBG40x3429
> #define PCI_DEVICE_ID_INTEL_IOAT_TBG50x342a
> #define PCI_DEVICE_ID_INTEL_IOAT_TBG60x342b
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Re: [PATCH] irq: add quirk for broken interrupt remapping on 55XX chipsets
On Sat, Mar 02, 2013 at 11:21:29AM -0500, Prarit Bhargava wrote:
> On 03/01/2013 12:17 PM, Neil Horman wrote:
> > A few years back intel published a spec update:
> > http://www.intel.com/content/dam/doc/specification-update/5520-and-5500-chipset-ioh-specification-update.pdf
> >
> > For the 5520 and 5500 chipsets which contained an errata (specificially
> > errata
> > 53), which noted that these chipsets can't properly do interrupt remapping,
> > and
> > as a result the recommend that interrupt remapping be disabled in bios.
> > While
> > many vendors have a bios update to do exactly that, not all do, and of
> > course
> > not all users update their bios to a level that corrects the problem. As a
> > result, occasionally interrupts can arrive at a cpu even after affinity for
> > that
> > interrupt has be moved, leading to lost or spurrious interrupts (usually
> > characterized by the message:
> > kernel: do_IRQ: 7.71 No irq handler for vector (irq -1)
> >
> > There have been several incidents recently of people seeing this error, and
> > investigation has shown that they have system for which their BIOS level is
> > such
> > that this feature was not properly turned off. As such, it would be good to
> > give them a reminder that their systems are vulnurable to this problem.
> >
> > Signed-off-by: Neil Horman
> > CC: Prarit Bhargava
> > CC: Don Zickus
> > CC: Don Dutile
> > CC: Bjorn Helgaas
> > CC: Asit Mallick
> > CC: linux-...@vger.kernel.org
> > ---
> > drivers/iommu/intel_irq_remapping.c | 20
> > include/linux/pci_ids.h | 2 ++
> > 2 files changed, 22 insertions(+)
> >
> > diff --git a/drivers/iommu/intel_irq_remapping.c
> > b/drivers/iommu/intel_irq_remapping.c
> > index f3b8f23..9bfb6c2 100644
> > --- a/drivers/iommu/intel_irq_remapping.c
> > +++ b/drivers/iommu/intel_irq_remapping.c
> > @@ -1113,3 +1113,23 @@ struct irq_remap_ops intel_irq_remap_ops = {
> > .msi_setup_irq = intel_msi_setup_irq,
> > .setup_hpet_msi = intel_setup_hpet_msi,
> > };
> > +
> > +
> > +static void intel_remapping_check(struct pci_dev *dev)
> > +{
> > + u8 revision;
> > +
> > + pci_read_config_byte(dev, PCI_REVISION_ID, &revision);
> > +
> > + if ((revision == 0x13) && irq_remapping_enabled) {
> > + pr_warn("WARNING WARNING WARNING WARNING WARNING WARNING\n"
> > + "This system BIOS has enabled interrupt remapping\n"
> > + "on a chipset that contains an errata making that\n"
> > + "feature unstable. Please reboot with nointremap\n"
> > + "added to the kernel command line and contact\n"
> > + "your BIOS vendor for an update");
>
> Make this one line? Might be too long but I believe the preferred policy is
> now
> to keep the output on one line so that it is easy to find in the kernel
> source.
>
> Also, IMO, remove the WARNING WARNING stuff.
>
> You also should probably use HW_ERR here too.
>
> P.
>
I can do that, I'll post version 2 on monday.
Neil
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Re: [PATCH] irq: add quirk for broken interrupt remapping on 55XX chipsets
On 03/04/2013 08:24 AM, Don Dutile wrote:
> On 03/02/2013 10:59 AM, Andreas Mohr wrote:
>> Hi,
>>
>>> if ((revision == 0x13)&& irq_remapping_enabled) {
>>> +pr_warn("WARNING WARNING WARNING WARNING WARNING
>>> WARNING\n"
>>> +"This system BIOS has enabled interrupt
>>> remapping\n"
>>> +"on a chipset that contains an errata making
>>> that\n"
>>> +"feature unstable. Please reboot with
>>> nointremap\n"
>>> +"added to the kernel command line and contact\n"
>>> +"your BIOS vendor for an update");
>>> +}
>>
>> Forgive me, but ISTR that there's a special BIOS firmware quirk bug
>> annotating
>> logger warning message mechanism (have I managed to hit all keywords yet? ;)
>> in the kernel which might be useful in this case.
>>
>>
>> OK, found something (but I don't think it was the mechanism
>> that ISTR - perhaps it got modernized?):
>>
>>
>> include/linux/printk.h:
>>
>> /*
>> * FW_BUG
>> * Add this to a message where you are sure the firmware is buggy or
>> * behaves
>> * really stupid or out of spec. Be aware that the responsible BIOS
>> * developer
>> * should be able to fix this issue or at least get a concrete idea of
>> * the
>> * problem by reading your message without the need of looking at the
>> * kernel
>> * code.
>> *
>> * Use it for definite and high priority BIOS bugs.
>> *
>> * FW_WARN
>> * Use it for not that clear (e.g. could the kernel messed up things
>> * already?)
>> * and medium priority BIOS bugs.
>> *
>> * FW_INFO
>> * Use this one if you want to tell the user or vendor about something
>> * suspicious, but generally harmless related to the firmware.
>> *
>> * Use it for information or very low priority BIOS bugs.
>> */
>>
>
> It is not a firmware/BIOS bug.
Correct. This is a hardware bug that *may be* resolved through a BIOS update.
But there is no guarantee that a BIOS update is available. Labelling it a FW
bug would be a mistake.
Prarit's comment to annotate it as
> a HW_ERR is more accurate. A software patch is being tested now
> to see if it can do set-affinity in a manner that avoids this race
> and enables IR to stay on for all these systems. It requires
> more testing to ensure the logic is valid. This patch was
> recommended as a necessary short-term fix, and to highlight to
> others this possible state -- which Gerry mentioned he had.
Yup -- as mstowe asked ... should we even consider this patch then, or should we
wait for the possible real fix?
Having said that ... I'm nervous about playing around with the set-affinity path
for this HW problem. We're basically changing good/reliable code for broken-ass
hardware. :/ That doesn't seem a like a good choice to me.
I can understand if we all feel that the code is broken, or it can be made
better -- but to change it because of bad HW just doesn't seem like the right
thing to do.
IMO.
P.
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Re: [PATCH] irq: add quirk for broken interrupt remapping on 55XX chipsets
On 03/02/2013 10:59 AM, Andreas Mohr wrote:
Hi,
if ((revision == 0x13)&& irq_remapping_enabled) {
+ pr_warn("WARNING WARNING WARNING WARNING WARNING
WARNING\n"
+ "This system BIOS has enabled interrupt
remapping\n"
+ "on a chipset that contains an errata making
that\n"
+ "feature unstable. Please reboot with
nointremap\n"
+ "added to the kernel command line and contact\n"
+ "your BIOS vendor for an update");
+ }
Forgive me, but ISTR that there's a special BIOS firmware quirk bug annotating
logger warning message mechanism (have I managed to hit all keywords yet? ;)
in the kernel which might be useful in this case.
OK, found something (but I don't think it was the mechanism
that ISTR - perhaps it got modernized?):
include/linux/printk.h:
/*
* FW_BUG
* Add this to a message where you are sure the firmware is buggy or
* behaves
* really stupid or out of spec. Be aware that the responsible BIOS
* developer
* should be able to fix this issue or at least get a concrete idea of
* the
* problem by reading your message without the need of looking at the
* kernel
* code.
*
* Use it for definite and high priority BIOS bugs.
*
* FW_WARN
* Use it for not that clear (e.g. could the kernel messed up things
* already?)
* and medium priority BIOS bugs.
*
* FW_INFO
* Use this one if you want to tell the user or vendor about something
* suspicious, but generally harmless related to the firmware.
*
* Use it for information or very low priority BIOS bugs.
*/
It is not a firmware/BIOS bug. Prarit's comment to annotate it as
a HW_ERR is more accurate. A software patch is being tested now
to see if it can do set-affinity in a manner that avoids this race
and enables IR to stay on for all these systems. It requires
more testing to ensure the logic is valid. This patch was
recommended as a necessary short-term fix, and to highlight to
others this possible state -- which Gerry mentioned he had.
Note: the race condition is a very small window, and could not
be duplicated on upstream kernel on known-failing-hw b/c
the interrupt rate dropped by 80%.
The errata's recommendation (to disable IR in the BIOS) makes
the option of a workaround impossible, since it will hide the
IR hw (no DMAR table for it). The BIOS 'update' may be avoided,
and corrected, if testing yields positive results, and after
posting, others don't see a flaw in the logic that was missed
by other reviewers.
So perhaps it is appropriate to be used here.
HTH,
Andreas Mohr
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