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Re: [Xen-devel] [PATCH] VT-d: improve RMRR validity checking

To: Weidong Han <weidong.han@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] VT-d: improve RMRR validity checking
From: Alex Williamson <alex.williamson@xxxxxx>
Date: Wed, 10 Mar 2010 19:32:01 -0700
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Noboru Iwamatsu <n_iwamatsu@xxxxxxxxxxxxxx>, "Cihula, Joseph" <joseph.cihula@xxxxxxxxx>, "Kay, Allen M" <allen.m.kay@xxxxxxxxx>, "linux@xxxxxxxxxxxxxx" <linux@xxxxxxxxxxxxxx>, "keir.fraser@xxxxxxxxxxxxx" <keir.fraser@xxxxxxxxxxxxx>
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On Thu, 2010-03-11 at 10:11 +0800, Weidong Han wrote:
> Alex, you are right. IOAPICs can be included in any DRHDs. Pls try 
> following patch, if no problem, I will submit it.

Thanks Weidong.  This of course works, but I still get this output:

(XEN) IOAPIC[0]: apic_id 8, version 32, address 0xfec00000, GSI 0-23
(XEN) IOAPIC[1]: apic_id 0, version 32, address 0xfec08000, GSI 24-47
(XEN) IOAPIC[2]: apic_id 10, version 32, address 0xfec10000, GSI 48-71
(XEN) Enabling APIC mode:  Phys.  Using 3 I/O APICs
(XEN) [VT-D]dmar.c:421:   Non-existent device (84:13.0) is reported in this 
DRHD's scope!
(XEN) [VT-D]dmar.c:442:   There are devices under device scope are not PCI 
discoverable! if xen fails at VT-d enabling, pls try option 

So now we've effectively relegated this code to printing things that
look like errors for both actual bad DMAR tables and 100% spec compliant
tables.  At a minimum, I think these dprintks need to be reduce to info
or debug level since they're effectively just spewing out noise.  Can't
we put a tag for the device type in the list of scope devices and skip
checking discoverable PCI devices for IOAPICs?  Do we need to do the
same for HPETs?  Thanks,


> diff -r cadf1bae9ee2 xen/drivers/passthrough/vtd/dmar.c
> --- a/xen/drivers/passthrough/vtd/dmar.c    Thu Feb 25 18:26:45 2010 +0800
> +++ b/xen/drivers/passthrough/vtd/dmar.c    Thu Mar 11 17:49:40 2010 +0800
> @@ -437,11 +437,9 @@ acpi_parse_one_drhd(struct acpi_dmar_ent
>              else
>              {
>                  dprintk(XENLOG_WARNING VTDPREFIX,
> -                    "  The DRHD is invalid due to there are devices under "
> -                    "its scope are not PCI discoverable! Pls try option "
> -                    "iommu=force or iommu=workaround_bios_bug if you "
> -                    "really want VT-d\n");
> -                ret = -EINVAL;
> +                    "  There are devices under device scope are not PCI "
> +                    "discoverable! if xen fails at VT-d enabling, pls try "
> +                    "option iommu=workaround_bios_bug.\n");
>              }
>          }
>          else

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