Re: 2.6.22-rc6-mm1 Intel DMAR crash on AMD x86_64

[Muli Ben-Yehuda <muli@il.ibm.com>]

On Fri, Jun 29, 2007 at 08:28:58AM -0700, Keshavamurthy, Anil S wrote:

> Here is the revised patch of the above.
> Andrew, please add this fix to
> +intel-iommu-dmar-detection-and-parsing-logic.patch
> ------------------------------------------------
> 
> Check for dmar_tbl pointer as this can be NULL on 
> systems with no Intel VT-d support.
> 
> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
> 
> ---
>  drivers/pci/dmar.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6.22-rc4-mm2/drivers/pci/dmar.c
> ===================================================================
> --- linux-2.6.22-rc4-mm2.orig/drivers/pci/dmar.c	2007-06-29 07:43:43.000000000 -0700
> +++ linux-2.6.22-rc4-mm2/drivers/pci/dmar.c	2007-06-29 07:46:25.000000000 -0700
> @@ -260,6 +260,8 @@
>  	int ret = 0;
>  
>  	dmar = (struct acpi_table_dmar *)dmar_tbl;
> +	if (!dmar)
> +		return -ENODEV;
>  
>  	if (!dmar->width) {
>  		printk (KERN_WARNING PREFIX "Zero: Invalid DMAR haw\n");
> @@ -301,7 +303,7 @@
>  
>  	parse_dmar_table();
>  	if (list_empty(&dmar_drhd_units)) {
> -		printk(KERN_ERR PREFIX "No DMAR devices found\n");
> +		printk(KERN_INFO PREFIX "No DMAR devices found\n");
>  		return -ENODEV;
>  	}
>  	return 0;

The convention is to print a KERN_DEBUG message if hardware is not
found when probing it, otherwise the boot messages become cluttered
with lots of "$FOO not found".

Cheers,
Muli