diff options
authorDavid Woodhouse <dwmw2@infradead.org>2009-11-19 02:18:44 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2009-11-19 13:42:02 -0800
commit5854d9c8d18359b1fc2f23c0ef2d51dd53281bd6 (patch)
parent66b00a7c93ec782d118d2c03bd599cfd041e80a1 (diff)
Fix handling of the HP/Acer 'DMAR at zero' BIOS error for machines with <4GiB RAM.
Commit 86cf898e1d0fca245173980e3897580db38569a8 ("intel-iommu: Check for 'DMAR at zero' BIOS error earlier.") was supposed to work by pretending not to detect an IOMMU if it was actually being reported by the BIOS at physical address zero. However, the intel_iommu_init() function is called unconditionally, as are the corresponding functions for other IOMMU hardware. So the patch only worked if you have RAM above the 4GiB boundary. It caused swiotlb to be initialised when no IOMMU was detected during early boot, and thus the later IOMMU init would refuse to run. But if you have less RAM than that, swiotlb wouldn't get set up and the IOMMU _would_ still end up being initialised, even though we never claimed to detect it. This patch also sets the dmar_disabled flag when the error is detected during the initial detection phase -- so that the later call to intel_iommu_init() will return without doing anything, regardless of whether swiotlb is used or not. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index e5f8fc164fd..b952ebc7a78 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -609,6 +609,9 @@ int __init check_zero_address(void)
+ dmar_disabled = 1;
return 0;