linux-kernel - Re: [lkp] [iommu/vt] 571dbbd4d04: DMAR-IR: Failed to copy IR table for dmar1 from previous kernel

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Date:	Thu, 02 Jul 2015 15:56:23 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	Joerg Roedel <jroedel@...e.de>
Cc:	LKML <linux-kernel@...r.kernel.org>, LKP ML <lkp@...org>
Subject: Re: [lkp] [iommu/vt] 571dbbd4d04: DMAR-IR: Failed to copy IR table
 for dmar1 from previous kernel

On Thu, 2015-07-02 at 08:39 +0200, Joerg Roedel wrote:
> On Thu, Jul 02, 2015 at 01:14:18PM +0800, Huang Ying wrote:
> > FYI, we noticed the below changes on
> > 
> > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
> > master
> > commit 571dbbd4d044e11c78bc077acb3ccef4c77b096e ("iommu/vt-d: Don't 
> > disable IR when it was previously enabled")
> > 
> > The following new message in kernel log may make end user 
> > confusing.
> > 
> > [    0.503764] DMAR-IR: IRQ remapping was enabled on dmar0 but we 
> > are not in kdump mode
> > [    0.512418] DMAR-IR: Failed to copy IR table for dmar0 from 
> > previous kernel
> > [    0.520501] DMAR-IR: IRQ remapping was enabled on dmar1 but we 
> > are not in kdump mode
> > [    0.529154] DMAR-IR: Failed to copy IR table for dmar1 from 
> > previous kernel
> > [    0.537077] DMAR-IR: Enabled IRQ remapping in x2apic mode
> 
> This is not a problem, the kernel detected that the IOMMU was already
> enabled, but it is not booting into a kdump kernel so it is not 
> trying
> to copy over translation tables. The messages for this case are 
> indeed a
> bit misleading, it looks like the kernel tried to copy the 
> translation
> tables, but it didn't. I'll fix this.
> 
> What were you doing to trigger this, it is quite uncommon to find the
> IOMMU enabled on a normal kernel boot. Did you boot with kexec into a
> new kernel?

Yes.  We use kexec to boot the new kernel.

Best Regards,
Huang, Ying

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