Xen devel - Oct 2009 - [PATCH] AMD IOMMU: Use global interrupt remapping table by default

Using a global interrupt remapping table shared by all devices has better 
compatibility with certain old BIOSes. Per-device interrupt remapping table 
can still be enabled by using a new parameter
"amd-iommu-perdev-intremap".
Thanks,
Wei

Signed-off-by: Wei Wang <wei.wang2@amd.com>
-- 
AMD GmbH, Germany
Operating System Research Center

Legal Information:
Advanced Micro Devices GmbH
Karl-Hammerschmidt-Str. 34
85609 Dornach b. München

Geschäftsführer: Andrew Bowd, Thomas M. McCoy, Giuliano Meroni
Sitz: Dornach, Gemeinde Aschheim, Landkreis München
Registergericht München, HRB Nr. 43632


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Wei,

Can you be more specific about which BIOSes behave poorly with
per-device intremap tables, and why?

The problem with a global intremap table is that, AFAICT, it''s not
fundamentally compatible with per-cpu IDTs.  With per-cpu IDTs,
different devices may end up with interrupts mapped to different cpus
but the same vector (i.e., device A mapped to cpu 9 vector 67, cpu B
mapped to cpu 12 vector 67).  This is by design; the whole point of
the per-cpu IDTs is to avoid restricting the number of IRQs to the
number of vectors.   But it seems that the intremap table only maps
vectors, not destination IDs; so in the example above, both devices''
interrupts would end up being remapped to the same place, causing one
device driver to get both sets of interrupts, and the other to get
none.

Do I understand correctly?  If so, it seems like we should switch to
per-device intremap tables by default; and if we''re using a global
intremap table, we need to somehow make sure that vectors are not
shared across cpus.

 -George

On Wed, Oct 28, 2009 at 4:32 PM, Wei Wang2 <wei.wang2@amd.com>
wrote:
> Using a global interrupt remapping table shared by all devices has better
> compatibility with certain old BIOSes. Per-device interrupt remapping table
> can still be enabled by using a new parameter
"amd-iommu-perdev-intremap".
> Thanks,
> Wei
>
> Signed-off-by: Wei Wang <wei.wang2@amd.com>
> --
> AMD GmbH, Germany
> Operating System Research Center
>
> Legal Information:
> Advanced Micro Devices GmbH
> Karl-Hammerschmidt-Str. 34
> 85609 Dornach b. München
>
> Geschäftsführer: Andrew Bowd, Thomas M. McCoy, Giuliano Meroni
> Sitz: Dornach, Gemeinde Aschheim, Landkreis München
> Registergericht München, HRB Nr. 43632
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>
>
_______________________________________________
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http://lists.xensource.com/xen-devel

On Tuesday 19 July 2011 16:14:31 George Dunlap wrote:
> Wei,
>
> Can you be more specific about which BIOSes behave poorly with
> per-device intremap tables, and why?
We found that, in some case, SATA device uses different device ids for dma 
remapping and interrupt remapping. Some early BIOSes cannot handle this 
situation correctly, so if SATA uses device id for DMA to lookup device table 
entry for intremap table and if intremap table is per-device configured, SATA 
device won''t get the right table.
> The problem with a global intremap table is that, AFAICT, it''s not
> fundamentally compatible with per-cpu IDTs.  With per-cpu IDTs,
> different devices may end up with interrupts mapped to different cpus
> but the same vector (i.e., device A mapped to cpu 9 vector 67, cpu B
> mapped to cpu 12 vector 67).  This is by design; the whole point of
> the per-cpu IDTs is to avoid restricting the number of IRQs to the
> number of vectors.   But it seems that the intremap table only maps
> vectors, not destination IDs; so in the example above, both
devices''
> interrupts would end up being remapped to the same place, causing one
> device driver to get both sets of interrupts, and the other to get
> none.
Yes, obviously a problem...Using shared intremap table, devices uses the same 
vector and delivery mode will end up to the same remapping entry. Is per-cpu 
IDTs enable by default in Xen?
> Do I understand correctly?  If so, it seems like we should switch to
> per-device intremap tables by default; and if we''re using a global
> intremap table, we need to somehow make sure that vectors are not
> shared across cpus.
I agree to use per-device table by default, since BIOS issue has been fixed 
and per-device table also has some security advantages.

Thanks,
Wei
>  -George
>
> On Wed, Oct 28, 2009 at 4:32 PM, Wei Wang2 <wei.wang2@amd.com> wrote:
> > Using a global interrupt remapping table shared by all devices has
better
> > compatibility with certain old BIOSes. Per-device interrupt remapping
> > table can still be enabled by using a new parameter
> > "amd-iommu-perdev-intremap". Thanks,
> > Wei
> >
> > Signed-off-by: Wei Wang <wei.wang2@amd.com>
> > --
> > AMD GmbH, Germany
> > Operating System Research Center
> >
> > Legal Information:
> > Advanced Micro Devices GmbH
> > Karl-Hammerschmidt-Str. 34
> > 85609 Dornach b. München
> >
> > Geschäftsführer: Andrew Bowd, Thomas M. McCoy, Giuliano Meroni
> > Sitz: Dornach, Gemeinde Aschheim, Landkreis München
> > Registergericht München, HRB Nr. 43632
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel



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On Wed, 2011-07-20 at 10:52 +0100, Wei Wang2 wrote:
> On Tuesday 19 July 2011 16:14:31 George Dunlap wrote:
> > Wei,
> >
> > Can you be more specific about which BIOSes behave poorly with
> > per-device intremap tables, and why?
> We found that, in some case, SATA device uses different device ids for dma 
> remapping and interrupt remapping. Some early BIOSes cannot handle this 
> situation correctly, so if SATA uses device id for DMA to lookup device
table
> entry for intremap table and if intremap table is per-device configured,
SATA
> device won''t get the right table.
Was this issue present in production BIOSes or do you mean early as in
pre-production? IOW can we drop the support non-share remapping table
altogether or do we need to fix things in this mode to force the IDT to
be identical across CPUs (either by resharing the IDT in that case, ick,
or by enforcing that the contents are the same for devices with this
property)?

OOI was the issue a confusion between the SATA PCI device and the legacy
PCI IDE facet of the same device?
> > The problem with a global intremap table is that, AFAICT,
it''s not
> > fundamentally compatible with per-cpu IDTs.  With per-cpu IDTs,
> > different devices may end up with interrupts mapped to different cpus
> > but the same vector (i.e., device A mapped to cpu 9 vector 67, cpu B
> > mapped to cpu 12 vector 67).  This is by design; the whole point of
> > the per-cpu IDTs is to avoid restricting the number of IRQs to the
> > number of vectors.   But it seems that the intremap table only maps
> > vectors, not destination IDs; so in the example above, both
devices''
> > interrupts would end up being remapped to the same place, causing one
> > device driver to get both sets of interrupts, and the other to get
> > none.
> 
> Yes, obviously a problem...Using shared intremap table, devices uses the
same
> vector and delivery mode will end up to the same remapping entry. Is
per-cpu
> IDTs enable by default in Xen?
I didn''t think it was even optional these days, but I didn''t
check.
> > Do I understand correctly?  If so, it seems like we should switch to
> > per-device intremap tables by default; and if we''re using a
global
> > intremap table, we need to somehow make sure that vectors are not
> > shared across cpus.
> I agree to use per-device table by default, since BIOS issue has been fixed
> and per-device table also has some security advantages.
> 
> Thanks,
> Wei
> 
> >  -George
> >
> > On Wed, Oct 28, 2009 at 4:32 PM, Wei Wang2 <wei.wang2@amd.com>
wrote:
> > > Using a global interrupt remapping table shared by all devices
has better
> > > compatibility with certain old BIOSes. Per-device interrupt
remapping
> > > table can still be enabled by using a new parameter
> > > "amd-iommu-perdev-intremap". Thanks,
> > > Wei
> > >
> > > Signed-off-by: Wei Wang <wei.wang2@amd.com>
> > > --
> > > AMD GmbH, Germany
> > > Operating System Research Center
> > >
> > > Legal Information:
> > > Advanced Micro Devices GmbH
> > > Karl-Hammerschmidt-Str. 34
> > > 85609 Dornach b. München
> > >
> > > Geschäftsführer: Andrew Bowd, Thomas M. McCoy, Giuliano Meroni
> > > Sitz: Dornach, Gemeinde Aschheim, Landkreis München
> > > Registergericht München, HRB Nr. 43632
> > >
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@lists.xensource.com
> > > http://lists.xensource.com/xen-devel
> 
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel


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Wednesday 20 July 2011 12:50:25 Ian Campbell wrote:
> On Wed, 2011-07-20 at 10:52 +0100, Wei Wang2 wrote:
> > On Tuesday 19 July 2011 16:14:31 George Dunlap wrote:
> > > Wei,
> > >
> > > Can you be more specific about which BIOSes behave poorly with
> > > per-device intremap tables, and why?
> >
> > We found that, in some case, SATA device uses different device ids for
> > dma remapping and interrupt remapping. Some early BIOSes cannot handle
> > this situation correctly, so if SATA uses device id for DMA to lookup
> > device table entry for intremap table and if intremap table is
per-device
> > configured, SATA device won''t get the right table.
>
> Was this issue present in production BIOSes or do you mean early as in
> pre-production? IOW can we drop the support non-share remapping table
> altogether or do we need to fix things in this mode to force the IDT to
> be identical across CPUs (either by resharing the IDT in that case, ick,
> or by enforcing that the contents are the same for devices with this
> property)?
>
> OOI was the issue a confusion between the SATA PCI device and the legacy
> PCI IDE facet of the same device?
Yes, using shared intremap table is the workaround for this issue. Ideally, 
BIOS should create 2 IVRS entries for SATA devices in IDE combined mode, one 
for DMA the other for interrupt. But this setup is not strict compatible with 
iommu specification. So recent BIOS should have IDE combined mode disabled in 
this case. So I believe that remove the global table is safe from now on. I 
could send patches.
Thanks,
Wei
> > > The problem with a global intremap table is that, AFAICT,
it''s not
> > > fundamentally compatible with per-cpu IDTs.  With per-cpu IDTs,
> > > different devices may end up with interrupts mapped to different
cpus
> > > but the same vector (i.e., device A mapped to cpu 9 vector 67,
cpu B
> > > mapped to cpu 12 vector 67).  This is by design; the whole point
of
> > > the per-cpu IDTs is to avoid restricting the number of IRQs to
the
> > > number of vectors.   But it seems that the intremap table only
maps
> > > vectors, not destination IDs; so in the example above, both
devices''
> > > interrupts would end up being remapped to the same place, causing
one
> > > device driver to get both sets of interrupts, and the other to
get
> > > none.
> >
> > Yes, obviously a problem...Using shared intremap table, devices uses
the
> > same vector and delivery mode will end up to the same remapping entry.
Is
> > per-cpu IDTs enable by default in Xen?
>
> I didn''t think it was even optional these days, but I
didn''t check.
>
> > > Do I understand correctly?  If so, it seems like we should switch
to
> > > per-device intremap tables by default; and if we''re
using a global
> > > intremap table, we need to somehow make sure that vectors are not
> > > shared across cpus.
> >
> > I agree to use per-device table by default, since BIOS issue has been
> > fixed and per-device table also has some security advantages.
> >
> > Thanks,
> > Wei
> >
> > >  -George
> > >
> > > On Wed, Oct 28, 2009 at 4:32 PM, Wei Wang2
<wei.wang2@amd.com> wrote:
> > > > Using a global interrupt remapping table shared by all
devices has
> > > > better compatibility with certain old BIOSes. Per-device
interrupt
> > > > remapping table can still be enabled by using a new
parameter
> > > > "amd-iommu-perdev-intremap". Thanks,
> > > > Wei
> > > >
> > > > Signed-off-by: Wei Wang <wei.wang2@amd.com>
> > > > --
> > > > AMD GmbH, Germany
> > > > Operating System Research Center
> > > >
> > > > Legal Information:
> > > > Advanced Micro Devices GmbH
> > > > Karl-Hammerschmidt-Str. 34
> > > > 85609 Dornach b. München
> > > >
> > > > Geschäftsführer: Andrew Bowd, Thomas M. McCoy, Giuliano
Meroni
> > > > Sitz: Dornach, Gemeinde Aschheim, Landkreis München
> > > > Registergericht München, HRB Nr. 43632
> > > >
> > > > _______________________________________________
> > > > Xen-devel mailing list
> > > > Xen-devel@lists.xensource.com
> > > > http://lists.xensource.com/xen-devel
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel



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On Wed, 2011-07-20 at 13:34 +0100, Wei Wang2 wrote:
> Wednesday 20 July 2011 12:50:25 Ian Campbell wrote:
> > On Wed, 2011-07-20 at 10:52 +0100, Wei Wang2 wrote:
> > > On Tuesday 19 July 2011 16:14:31 George Dunlap wrote:
> > > > Wei,
> > > >
> > > > Can you be more specific about which BIOSes behave poorly
with
> > > > per-device intremap tables, and why?
> > >
> > > We found that, in some case, SATA device uses different device
ids for
> > > dma remapping and interrupt remapping. Some early BIOSes cannot
handle
> > > this situation correctly, so if SATA uses device id for DMA to
lookup
> > > device table entry for intremap table and if intremap table is
per-device
> > > configured, SATA device won''t get the right table.
> >
> > Was this issue present in production BIOSes or do you mean early as in
> > pre-production? IOW can we drop the support non-share remapping table
> > altogether or do we need to fix things in this mode to force the IDT
to
> > be identical across CPUs (either by resharing the IDT in that case,
ick,
> > or by enforcing that the contents are the same for devices with this
> > property)?
> >
> > OOI was the issue a confusion between the SATA PCI device and the
legacy
> > PCI IDE facet of the same device?
> 
> Yes, using shared intremap table is the workaround for this issue. Ideally,
> BIOS should create 2 IVRS entries for SATA devices in IDE combined mode,
one
> for DMA the other for interrupt. But this setup is not strict compatible
with
> iommu specification. So recent BIOS should have IDE combined mode disabled
in
> this case. So I believe that remove the global table is safe from now on. I
> could send patches.
Please do.

Ian.
> Thanks,
> Wei
> 
> > > > The problem with a global intremap table is that, AFAICT,
it''s not
> > > > fundamentally compatible with per-cpu IDTs.  With per-cpu
IDTs,
> > > > different devices may end up with interrupts mapped to
different cpus
> > > > but the same vector (i.e., device A mapped to cpu 9 vector
67, cpu B
> > > > mapped to cpu 12 vector 67).  This is by design; the whole
point of
> > > > the per-cpu IDTs is to avoid restricting the number of IRQs
to the
> > > > number of vectors.   But it seems that the intremap table
only maps
> > > > vectors, not destination IDs; so in the example above, both
devices''
> > > > interrupts would end up being remapped to the same place,
causing one
> > > > device driver to get both sets of interrupts, and the other
to get
> > > > none.
> > >
> > > Yes, obviously a problem...Using shared intremap table, devices
uses the
> > > same vector and delivery mode will end up to the same remapping
entry. Is
> > > per-cpu IDTs enable by default in Xen?
> >
> > I didn''t think it was even optional these days, but I
didn''t check.
> >
> > > > Do I understand correctly?  If so, it seems like we should
switch to
> > > > per-device intremap tables by default; and if we''re
using a global
> > > > intremap table, we need to somehow make sure that vectors
are not
> > > > shared across cpus.
> > >
> > > I agree to use per-device table by default, since BIOS issue has
been
> > > fixed and per-device table also has some security advantages.
> > >
> > > Thanks,
> > > Wei
> > >
> > > >  -George
> > > >
> > > > On Wed, Oct 28, 2009 at 4:32 PM, Wei Wang2
<wei.wang2@amd.com> wrote:
> > > > > Using a global interrupt remapping table shared by all
devices has
> > > > > better compatibility with certain old BIOSes.
Per-device interrupt
> > > > > remapping table can still be enabled by using a new
parameter
> > > > > "amd-iommu-perdev-intremap". Thanks,
> > > > > Wei
> > > > >
> > > > > Signed-off-by: Wei Wang <wei.wang2@amd.com>
> > > > > --
> > > > > AMD GmbH, Germany
> > > > > Operating System Research Center
> > > > >
> > > > > Legal Information:
> > > > > Advanced Micro Devices GmbH
> > > > > Karl-Hammerschmidt-Str. 34
> > > > > 85609 Dornach b. München
> > > > >
> > > > > Geschäftsführer: Andrew Bowd, Thomas M. McCoy, Giuliano
Meroni
> > > > > Sitz: Dornach, Gemeinde Aschheim, Landkreis München
> > > > > Registergericht München, HRB Nr. 43632
> > > > >
> > > > > _______________________________________________
> > > > > Xen-devel mailing list
> > > > > Xen-devel@lists.xensource.com
> > > > > http://lists.xensource.com/xen-devel
> > >
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@lists.xensource.com
> > > http://lists.xensource.com/xen-devel
> 
> 
> 


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George & Ian,
Patch attached. This patch removes global interrupt remapping table and uses 
per-device table instead. This should work with per-cpu IDTs.  We are safe to 
remove global table since SATA device id issue dose not appear in recent 
production BIOS.
Thanks,
Wei

Signed-off-by: Wei Wang <wei.wang2@amd.com>
--
Advanced Micro Devices GmbH
Sitz: Dornach, Gemeinde Aschheim, 
Landkreis München Registergericht München, 
HRB Nr. 43632 WEEE Registrierungsnummer 129 19551
Geschäftsführer:
Alberto BozzoOn 

Wednesday 20 July 2011 15:01:35 Ian Campbell wrote:
> On Wed, 2011-07-20 at 13:34 +0100, Wei Wang2 wrote:
> > Wednesday 20 July 2011 12:50:25 Ian Campbell wrote:
> > > On Wed, 2011-07-20 at 10:52 +0100, Wei Wang2 wrote:
> > > > On Tuesday 19 July 2011 16:14:31 George Dunlap wrote:
> > > > > Wei,
> > > > >
> > > > > Can you be more specific about which BIOSes behave
poorly with
> > > > > per-device intremap tables, and why?
> > > >
> > > > We found that, in some case, SATA device uses different
device ids
> > > > for dma remapping and interrupt remapping. Some early BIOSes
cannot
> > > > handle this situation correctly, so if SATA uses device id
for DMA to
> > > > lookup device table entry for intremap table and if intremap
table is
> > > > per-device configured, SATA device won''t get the
right table.
> > >
> > > Was this issue present in production BIOSes or do you mean early
as in
> > > pre-production? IOW can we drop the support non-share remapping
table
> > > altogether or do we need to fix things in this mode to force the
IDT to
> > > be identical across CPUs (either by resharing the IDT in that
case,
> > > ick, or by enforcing that the contents are the same for devices
with
> > > this property)?
> > >
> > > OOI was the issue a confusion between the SATA PCI device and the
> > > legacy PCI IDE facet of the same device?
> >
> > Yes, using shared intremap table is the workaround for this issue.
> > Ideally, BIOS should create 2 IVRS entries for SATA devices in IDE
> > combined mode, one for DMA the other for interrupt. But this setup is
not
> > strict compatible with iommu specification. So recent BIOS should have
> > IDE combined mode disabled in this case. So I believe that remove the
> > global table is safe from now on. I could send patches.
>
> Please do.
>
> Ian.
>
> > Thanks,
> > Wei
> >
> > > > > The problem with a global intremap table is that,
AFAICT, it''s not
> > > > > fundamentally compatible with per-cpu IDTs.  With
per-cpu IDTs,
> > > > > different devices may end up with interrupts mapped to
different
> > > > > cpus but the same vector (i.e., device A mapped to cpu
9 vector 67,
> > > > > cpu B mapped to cpu 12 vector 67).  This is by design;
the whole
> > > > > point of the per-cpu IDTs is to avoid restricting the
number of
> > > > > IRQs to the number of vectors.   But it seems that the
intremap
> > > > > table only maps vectors, not destination IDs; so in the
example
> > > > > above, both devices'' interrupts would end up
being remapped to the
> > > > > same place, causing one device driver to get both sets
of
> > > > > interrupts, and the other to get none.
> > > >
> > > > Yes, obviously a problem...Using shared intremap table,
devices uses
> > > > the same vector and delivery mode will end up to the same
remapping
> > > > entry. Is per-cpu IDTs enable by default in Xen?
> > >
> > > I didn''t think it was even optional these days, but I
didn''t check.
> > >
> > > > > Do I understand correctly?  If so, it seems like we
should switch
> > > > > to per-device intremap tables by default; and if
we''re using a
> > > > > global intremap table, we need to somehow make sure
that vectors
> > > > > are not shared across cpus.
> > > >
> > > > I agree to use per-device table by default, since BIOS issue
has been
> > > > fixed and per-device table also has some security
advantages.
> > > >
> > > > Thanks,
> > > > Wei
> > > >
> > > > >  -George
> > > > >
> > > > > On Wed, Oct 28, 2009 at 4:32 PM, Wei Wang2
<wei.wang2@amd.com>
wrote:
> > > > > > Using a global interrupt remapping table shared by
all devices
> > > > > > has better compatibility with certain old BIOSes.
Per-device
> > > > > > interrupt remapping table can still be enabled by
using a new
> > > > > > parameter "amd-iommu-perdev-intremap".
Thanks,
> > > > > > Wei
> > > > > >
> > > > > > Signed-off-by: Wei Wang <wei.wang2@amd.com>
> > > > > > --
> > > > > > AMD GmbH, Germany
> > > > > > Operating System Research Center
> > > > > >
> > > > > > Legal Information:
> > > > > > Advanced Micro Devices GmbH
> > > > > > Karl-Hammerschmidt-Str. 34
> > > > > > 85609 Dornach b. München
> > > > > >
> > > > > > Geschäftsführer: Andrew Bowd, Thomas M. McCoy,
Giuliano Meroni
> > > > > > Sitz: Dornach, Gemeinde Aschheim, Landkreis
München
> > > > > > Registergericht München, HRB Nr. 43632
> > > > > >
> > > > > > _______________________________________________
> > > > > > Xen-devel mailing list
> > > > > > Xen-devel@lists.xensource.com
> > > > > > http://lists.xensource.com/xen-devel
> > > >
> > > > _______________________________________________
> > > > Xen-devel mailing list
> > > > Xen-devel@lists.xensource.com
> > > > http://lists.xensource.com/xen-devel



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On Wed, Jul 20, 2011 at 4:56 PM, Wei Wang2 <wei.wang2@amd.com>
wrote:
> George & Ian,
> Patch attached. This patch removes global interrupt remapping table and
uses
> per-device table instead. This should work with per-cpu IDTs.  We are safe
to
> remove global table since SATA device id issue dose not appear in recent
> production BIOS.
Exactly how "recent" are these BIOSes?  Or I guess alternately, how
old are the BIOSes that broke?

We still have customers who seem to have hardware that''s several years
old; if the answer isn''t something like "8 years", it may be
better to
just change the default setting.

 -George

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On Thursday 21 July 2011 11:07:40 George Dunlap wrote:
> On Wed, Jul 20, 2011 at 4:56 PM, Wei Wang2 <wei.wang2@amd.com> wrote:
> > George & Ian,
> > Patch attached. This patch removes global interrupt remapping table
and
> > uses per-device table instead. This should work with per-cpu IDTs.  We
> > are safe to remove global table since SATA device id issue dose not
> > appear in recent production BIOS.
>
> Exactly how "recent" are these BIOSes?  Or I guess alternately,
how
> old are the BIOSes that broke?
George,
Actually, we encountered this issue about 2 years ago and fixed this in BIOS. 
There should be very less productions shipped the mark at that time (probably 
none) and all newer products after that should absorb this fix. Even without 
BIOS fix, user can always disable IDE mode from BIOS menu manually if they 
were hit by this issue. So basically, I think removing global table is also 
reasonable.  
Thanks
Wei
> We still have customers who seem to have hardware that''s several
years
> old; if the answer isn''t something like "8 years", it
may be better to
> just change the default setting.
>
>  -George



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On Thu, Jul 21, 2011 at 11:38 AM, Wei Wang2 <wei.wang2@amd.com>
wrote:
> On Thursday 21 July 2011 11:07:40 George Dunlap wrote:
>> On Wed, Jul 20, 2011 at 4:56 PM, Wei Wang2 <wei.wang2@amd.com>
wrote:
>> > George & Ian,
>> > Patch attached. This patch removes global interrupt remapping
table and
>> > uses per-device table instead. This should work with per-cpu IDTs.
 We
>> > are safe to remove global table since SATA device id issue dose
not
>> > appear in recent production BIOS.
>>
>> Exactly how "recent" are these BIOSes?  Or I guess
alternately, how
>> old are the BIOSes that broke?
>
> George,
> Actually, we encountered this issue about 2 years ago and fixed this in
BIOS.
> There should be very less productions shipped the mark at that time
(probably
> none) and all newer products after that should absorb this fix. Even
without
> BIOS fix, user can always disable IDE mode from BIOS menu manually if they
> were hit by this issue. So basically, I think removing global table is also
> reasonable.
Sounds reasonable to me.

Acked-by: George Dunlap <george.dunlap@eu.citirx.com>
> Thanks
> Wei
>
>> We still have customers who seem to have hardware that''s
several years
>> old; if the answer isn''t something like "8 years",
it may be better to
>> just change the default setting.
>>
>>  -George
>
>
>
>
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> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>
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