git-latest: kernel oops in IOMMU setup
From: Dirk Hohndel
Date: Thu Jan 08 2009 - 15:06:21 EST
latest git from Linus. On a Thinkpad x200s with VT-d enabled (if I
disable VT-d, this of course goes away).
The oops happens very early during boot in device_to_iommu (called
from domain_context_mapping_one).
Looking at the code dump and the disassembled function here's where
the error happens:
static struct intel_iommu *device_to_iommu(u8 bus, u8 devfn)
{
struct dmar_drhd_unit *drhd = NULL;
int i;
for_each_drhd_unit(drhd) {
if (drhd->ignored)
continue;
for (i = 0; i < drhd->devices_cnt; i++)
if (drhd->devices[i]->bus->number == bus &&
--> drhd->devices[0] is NULL
drhd->devices[i]->devfn == devfn)
return drhd->iommu;
Given how early this happens it's a little hard to provide logs, etc. I
literally used delay_boot=100 and wrote things down by hand (forgot my
digital camera) and then added printk's to verify).
please let me know what other data I should collect.
The system ran fine with the 2.6.28 release kernel.
/D
--
Dirk Hohndel
Intel Open Source Technology Center
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