Prior to these IOMMU patches, the passthrough option
could not be used because it would cause the kernel to
panic. Provide an indication that a kernel is capable
of handling passthrough mode through the introduction
of a specific variable name. This allows automatic
configuration utilities to set the "iommu=pt" kernel
cmdline option safely.
Signed-off-by: Mike Travis <[email protected]>
Acked-by: Dimitri Sivanich <[email protected]>
---
drivers/pci/intel-iommu.c | 4 ++++
1 file changed, 4 insertions(+)
--- linux.orig/drivers/pci/intel-iommu.c
+++ linux/drivers/pci/intel-iommu.c
@@ -390,6 +390,9 @@ static int dmar_map_gfx = 1;
static int dmar_forcedac;
static int intel_iommu_strict;
+/* specifically named variable that indicates "iommu=pt" is available */
+static int __initdata intel_iommu_64bit_pt;
+
#define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
static DEFINE_SPINLOCK(device_domain_lock);
static LIST_HEAD(device_domain_list);
@@ -425,6 +428,7 @@ static int __init intel_iommu_setup(char
while (*str == ',')
str++;
}
+ intel_iommu_64bit_pt = 1;
return 0;
}
__setup("intel_iommu=", intel_iommu_setup);
--
On Thu, 2011-05-26 at 20:32 -0500, Mike Travis wrote:
> Prior to these IOMMU patches, the passthrough option
> could not be used because it would cause the kernel to
> panic.
Could not be used on certain hardware? In certain configurations? It
wasn't just *completely* broken (unless it got broken in a recent
regression).
> Provide an indication that a kernel is capable
> of handling passthrough mode through the introduction
> of a specific variable name. This allows automatic
> configuration utilities to set the "iommu=pt" kernel
> cmdline option safely.
That implies that there is a follow-up patch to somehow export this
information to userspace? Where the information in question is just the
fact that a certain set of bugs have been fixed?
Since these *are* actually bugs, and not new features, I take it we're
looking at merging them for 2.6.40? I was planning to ask Linus to pull
my tree today, and I'm not entirely happy with merging them at the last
minute.
So I'll plan to merge them into my tree after the outstanding merge, and
then perhaps ask Linus to take them *after* -rc1? Since they're actually
bug fixes, I suspect that's the best way to proceed?
--
dwmw2