linux-next: manual merge of the dwmw2-iommu tree with Linus' tree

linux-next: manual merge of the dwmw2-iommu tree with Linus' tree

[Stephen Rothwell]

Hi David,

Today's linux-next merge of the dwmw2-iommu tree got a conflict in
arch/x86/kernel/apic/apic.c between commit 31dce14a3269 ("x86, ioapic:
Use ioapic_saved_data while enabling intr-remapping") from Linus' tree and
commit 6a87c5ec6463 ("intel-iommu: enable x2apic opt out") from the
dwmw2-iommu tree.

I fixed it up (see below) and can carry the fix as necessary.
-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au

diff --cc arch/x86/kernel/apic/apic.c
index b961af8,fb1c36c..0000000
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@@ -1461,16 -1450,24 +1461,17 @@@ int __init enable_IR(void
  void __init enable_IR_x2apic(void)
  {
  	unsigned long flags;
- 	int ret, x2apic_enabled = 0;
 -	struct IO_APIC_route_entry **ioapic_entries;
+ 	int ret = 0, x2apic_enabled = 0;
  	int dmar_table_init_ret;
  
  	dmar_table_init_ret = dmar_table_init();
- 	if (dmar_table_init_ret && !x2apic_supported())
+ 	if (dmar_table_init_ret && !cpu_has_x2apic)
  		return;
  
 -	ioapic_entries = alloc_ioapic_entries();
 -	if (!ioapic_entries) {
 -		pr_err("Allocate ioapic_entries failed\n");
 -		goto out;
 -	}
 -
 -	ret = save_IO_APIC_setup(ioapic_entries);
 +	ret = save_ioapic_entries();
  	if (ret) {
  		pr_info("Saving IO-APIC state failed: %d\n", ret);
+ 		ret = 0;
  		goto out;
  	}
  

Re: linux-next: manual merge of the dwmw2-iommu tree with Linus' tree

[Ingo Molnar]

* Stephen Rothwell <sfr@canb.auug.org.au> wrote:

> Hi David,
> 
> Today's linux-next merge of the dwmw2-iommu tree got a conflict in
> arch/x86/kernel/apic/apic.c between commit 31dce14a3269 ("x86, ioapic:
> Use ioapic_saved_data while enabling intr-remapping") from Linus' tree and
> commit 6a87c5ec6463 ("intel-iommu: enable x2apic opt out") from the
> dwmw2-iommu tree.

David, please do not modify arch/x86/kernel/apic/apic.c but send such 
patches to the x86 maintainers!

That particular change was still under discussion and i'm not at all 
sure we want to do it like that. So please repost the latest version.

Thanks,

	Ingo

Re: linux-next: manual merge of the dwmw2-iommu tree with Linus' tree

[David Woodhouse]

On Wed, 25 May 2011, Ingo Molnar wrote:

> That particular change was still under discussion and i'm not at all 
> sure we want to do it like that. So please repost the latest version.

I had not seen such discussion; I had the impression that having dealt 
with my feedback about making the thing more visible to the user, Youquan
considered the patch complete.

I am more than happy to absolve responsibility for this patch altogether 
and drop it from tree, though. It is *absolutely* the wrong approach, in 
my opinion. If the BIOS is broken and cannot cope with x2apic, the 
solution is to line the "engineers" responsible up against the wall and 
shoot them. And then to implement a "quiesce all SMI" feature that the OS 
can invoke, and make it mandatory. Presumably that's the underlying 
problem they were trying to solve?

The answer certainly isn't to add a flag in the DMAR table to opt out of 
x2apic use, when afaict the kernel is capable of using x2apic in some 
cases even when the *is* no DMAR. (Either that, or we have a lot of dead 
code in that area which *looks* like it copes with x2apic+!dmar).

I'll drop this patch from my tree when I get home and happily wash my 
hands of it. It's all yours; have fun :)

-- 
dwmw2

Re: linux-next: manual merge of the dwmw2-iommu tree with Linus' tree

[Ingo Molnar]

* David Woodhouse <dwmw2@infradead.org> wrote:

> On Wed, 25 May 2011, Ingo Molnar wrote:
> 
> > That particular change was still under discussion and i'm not at all 
> > sure we want to do it like that. So please repost the latest version.
> 
> I had not seen such discussion; I had the impression that having dealt 
> with my feedback about making the thing more visible to the user, Youquan
> considered the patch complete.

I lurked your discussion with Youquan and expected another iteration 
posted. I was keeping my gun powder dry for the next round because i 
saw you reaping the patch to pieces already and there was nothing 
more to say really :)

> I am more than happy to absolve responsibility for this patch 
> altogether and drop it from tree, though. It is *absolutely* the 
> wrong approach, in my opinion. If the BIOS is broken and cannot 
> cope with x2apic, the solution is to line the "engineers" 
> responsible up against the wall and shoot them. And then to 
> implement a "quiesce all SMI" feature that the OS can invoke, and 
> make it mandatory. Presumably that's the underlying problem they 
> were trying to solve?
> 
> The answer certainly isn't to add a flag in the DMAR table to opt 
> out of x2apic use, when afaict the kernel is capable of using 
> x2apic in some cases even when the *is* no DMAR. (Either that, or 
> we have a lot of dead code in that area which *looks* like it copes 
> with x2apic+!dmar).

Yeah, that was exactly my main concern as well: why should we allow 
the BIOS to tell us not to use a CPU feature that the CPU tells us is 
usable?

We generally do not allow such level of BIOS control. They should fix 
the BIOS to not generate DMAR tables at all if they want us to 'opt 
out', or ship a CPU without x2apic (or a CPU microcode version that 
turns off the x2apic CPUID bit or whatever).

So unless i missed some fine detail of control here, the whole idea 
of generating DMAR tables (which were always inherently connected to 
x2apic really) that tell us 'never mind about x2apic!' seems rather 
counter-productive ...

> I'll drop this patch from my tree when I get home and happily wash 
> my hands of it. It's all yours; have fun :)

Thanks. Youquan, mind resending the latest and greatest version so we 
can continue flami^W iterating it? Please also Cc: David.

Thanks,

	Ingo

Re: linux-next: manual merge of the dwmw2-iommu tree with Linus' tree

[Youquan Song]

On Wed, May 25, 2011 at 01:00:04PM +1000, Stephen Rothwell wrote:
> Hi David,
> 
> Today's linux-next merge of the dwmw2-iommu tree got a conflict in
> arch/x86/kernel/apic/apic.c between commit 31dce14a3269 ("x86, ioapic:
> Use ioapic_saved_data while enabling intr-remapping") from Linus' tree and
> commit 6a87c5ec6463 ("intel-iommu: enable x2apic opt out") from the
> dwmw2-iommu tree.
> 
> I fixed it up (see below) and can carry the fix as necessary.

The fix looks good to me.

Thanks
-Youquan

Re: linux-next: manual merge of the dwmw2-iommu tree with Linus' tree

[David Woodhouse]

On Wed, 2011-05-25 at 13:00 +1000, Stephen Rothwell wrote:
> Today's linux-next merge of the dwmw2-iommu tree got a conflict in
> arch/x86/kernel/apic/apic.c between commit 31dce14a3269 ("x86, ioapic:
> Use ioapic_saved_data while enabling intr-remapping") from Linus' tree and
> commit 6a87c5ec6463 ("intel-iommu: enable x2apic opt out") from the
> dwmw2-iommu tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. 

Offending patch dropped.

The machine hosting git.infradead.org is going down shortly, and will be
coming up in a new home tomorrow morning Boston time (EDT/GMT-5). Please
could you use this git repository instead for the iommu tree, for
"tonight's" linux-next:
    git://git.kernel.org/pub/scm/linux/kernel/git/dwmw2/iommu-2.6.git

(or ssh://master.kernel.org/pub/scm/linux/kernel/git/dwmw2/iommu-2.6.git
if it hasn't propagated to the mirrors in time)

Thanks.

The mtd tree hasn't changed in the last day, so no need to use a
separate URL for that; the last pull is fine, right?

-- 
dwmw2