path: root/scripts/mod/file2alias.c
diff options
authorAndi Kleen <ak@linux.intel.com>2012-01-26 00:09:05 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2012-01-26 16:44:41 -0800
commit644e9cbbe3fc032cc92d0936057e166a994dc246 (patch)
tree46f0c35d92419dcedf19067a060e7877dc3d6b28 /scripts/mod/file2alias.c
parentdebugfs: add mode, uid and gid options (diff)
Add driver auto probing for x86 features v4
There's a growing number of drivers that support a specific x86 feature or CPU. Currently loading these drivers currently on a generic distribution requires various driver specific hacks and it often doesn't work. This patch adds auto probing for drivers based on the x86 cpuid information, in particular based on vendor/family/model number and also based on CPUID feature bits. For example a common issue is not loading the SSE 4.2 accelerated CRC module: this can significantly lower the performance of BTRFS which relies on fast CRC. Another issue is loading the right CPUFREQ driver for the current CPU. Currently distributions often try all all possible driver until one sticks, which is not really a good way to do this. It works with existing udev without any changes. The code exports the x86 information as a generic string in sysfs that can be matched by udev's pattern matching. This scheme does not support numeric ranges, so if you want to handle e.g. ranges of model numbers they have to be encoded in ASCII or simply all models or families listed. Fixing that would require changing udev. Another issue is that udev will happily load all drivers that match, there is currently no nice way to stop a specific driver from being loaded if it's not needed (e.g. if you don't need fast CRC) But there are not that many cpu specific drivers around and they're all not that bloated, so this isn't a particularly serious issue. Originally this patch added the modalias to the normal cpu sysdevs. However sysdevs don't have all the infrastructure needed for udev, so it couldn't really autoload drivers. This patch instead adds the CPU modaliases to the cpuid devices, which are real devices with full support for udev. This implies that the cpuid driver has to be loaded to use this. This patch just adds infrastructure, some driver conversions in followups. Thanks to Kay for helping with some sysfs magic. v2: Constifcation, some updates v4: (trenn@suse.de): - Use kzalloc instead of kmalloc to terminate modalias buffer - Use uppercase hex values to match correctly against hex values containing letters Cc: Dave Jones <davej@redhat.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jen Axboe <axboe@kernel.dk> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Huang Ying <ying.huang@intel.com> Cc: Len Brown <lenb@kernel.org> Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Thomas Renninger <trenn@suse.de> Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'scripts/mod/file2alias.c')
1 files changed, 24 insertions, 0 deletions
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index c0e14b3f2306..026ba38759ca 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -1013,6 +1013,30 @@ static int do_amba_entry(const char *filename,
ADD_TO_DEVTABLE("amba", struct amba_id, do_amba_entry);
+/* LOOKS like x86cpu:vendor:VVVV:family:FFFF:model:MMMM:feature:*,FEAT,*
+ * All fields are numbers. It would be nicer to use strings for vendor
+ * and feature, but getting those out of the build system here is too
+ * complicated.
+ */
+static int do_x86cpu_entry(const char *filename, struct x86_cpu_id *id,
+ char *alias)
+ id->feature = TO_NATIVE(id->feature);
+ id->family = TO_NATIVE(id->family);
+ id->model = TO_NATIVE(id->model);
+ id->vendor = TO_NATIVE(id->vendor);
+ strcpy(alias, "x86cpu:");
+ ADD(alias, "vendor:", id->vendor != X86_VENDOR_ANY, id->vendor);
+ ADD(alias, ":family:", id->family != X86_FAMILY_ANY, id->family);
+ ADD(alias, ":model:", id->model != X86_MODEL_ANY, id->model);
+ ADD(alias, ":feature:*,", id->feature != X86_FEATURE_ANY, id->feature);
+ strcat(alias, ",*");
+ return 1;
+ADD_TO_DEVTABLE("x86cpu", struct x86_cpu_id, do_x86cpu_entry);
/* Does namelen bytes of name exactly match the symbol? */
static bool sym_is(const char *name, unsigned namelen, const char *symbol)