DMI-based module autoloading, second try

From: Lennart Poettering <[email protected]>

This is the second version of the patch I sent yesterday which adds DMI-based module autoloading to the Linux kernel. I fixed all the issues Björn Steinbrink pointed out. (Thanks, btw!)

Again, the explanation:

The patch below adds DMI/SMBIOS based module autoloading to the Linux kernel. The idea is to load laptop drivers automatically (and other drivers which cannot be autoloaded otherwise), based on the DMI system identification information of the BIOS.

Right now most distros manually try to load all available laptop drivers on bootup in the hope that at least one of them loads successfully. This patch does away with all that, and uses udev to automatically load matching drivers on the right machines.

Basically the patch just exports the DMI information that has been parsed by the kernel anyway to userspace via a sysfs device /sys/class/dmi/id and makes sure that proper modalias attributes are available. Besides adding the "modalias" attribute it also adds attributes for a few other DMI fields which might be useful for writing udev rules.

This patch is not an attempt to export the entire DMI/SMBIOS data to userspace. We already have "dmidecode" which parses the complete DMI info from userspace. The purpose of this patch is machine model identification and good udev integration.

To take advantage of DMI based module autoloading, a driver should export one or more MODULE_ALIAS fields similar to these:

MODULE_ALIAS("dmi:*:svnMICRO-STARINT'LCO.,LTD:pnMS-1013:pvr0131*:cvnMICRO-STARINT'LCO.,LTD:ct10:*"); MODULE_ALIAS("dmi:*:svnMicro-StarInternational:pnMS-1058:pvr0581:rvnMSI:rnMS-1058:*:ct10:*"); MODULE_ALIAS("dmi:*:svnMicro-StarInternational:pnMS-1412:*:rvnMSI:rnMS-1412:*:cvnMICRO-STARINT'LCO.,LTD:ct10:*"); MODULE_ALIAS("dmi:*:svnNOTEBOOK:pnSAM2000:pvr0131*:cvnMICRO-STARINT'LCO.,LTD:ct10:*");

These lines are specific to my msi-laptop.c driver. They are basically just a concatenation of a few carefully selected DMI fields with all potentially bad characters stripped.

Besides laptop drivers, modules like "hdaps", the i2c modules and the hwmon modules are good candidates for "dmi:" MODULE_ALIAS lines.

Besides merely exporting the DMI data via sysfs the patch adds support for a few more DMI fields. Especially the CHASSIS fields are very useful to identify different laptop modules. The patch also adds working MODULE_ALIAS lines to my msi-laptop.c driver.

I'd like to thank Kay Sievers for helping me to clean up this patch for posting it on lkml.

Patch is against Linus' current GIT HEAD. Should probably apply to older kernels as well without modification.

Please merge,

Lennart

---
 drivers/firmware/Kconfig    |    9 +
 drivers/firmware/Makefile   |    1 
 drivers/firmware/dmi-id.c   |  225 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/firmware/dmi_scan.c |   73 +++++++++++++-
 drivers/misc/msi-laptop.c   |   44 ++++++++
 include/linux/dmi.h         |    8 +
 6 files changed, 351 insertions(+), 9 deletions(-)

@@ -84,4 +84,13 @@ config DCDBAS
 	  Say Y or M here to enable the driver for use by Dell systems
 	  management software such as Dell OpenManage.
 
+config DMIID
+    bool "Export DMI identification via sysfs to userspace"
+    depends on DMI
+    default y
+	help
+	  Say Y here if you want to query SMBIOS/DMI system identification
+	  information from userspace through /sys/class/dmi/id/ or if you want
+	  DMI-based module auto-loading.
+
 endmenu

@@ -7,3 +7,4 @@ obj-$(CONFIG_EFI_VARS)		+= efivars.o
 obj-$(CONFIG_EFI_PCDP)		+= pcdp.o
 obj-$(CONFIG_DELL_RBU)          += dell_rbu.o
 obj-$(CONFIG_DCDBAS)		+= dcdbas.o
+obj-$(CONFIG_DMIID)		+= dmi-id.o

@@ -12,9 +12,17 @@ enum dmi_field {
 	DMI_PRODUCT_NAME,
 	DMI_PRODUCT_VERSION,
 	DMI_PRODUCT_SERIAL,
+	DMI_PRODUCT_UUID,
 	DMI_BOARD_VENDOR,
 	DMI_BOARD_NAME,
 	DMI_BOARD_VERSION,
+	DMI_BOARD_SERIAL,
+	DMI_BOARD_ASSET_TAG,
+	DMI_CHASSIS_VENDOR,
+	DMI_CHASSIS_TYPE,
+	DMI_CHASSIS_VERSION,
+	DMI_CHASSIS_SERIAL,
+	DMI_CHASSIS_ASSET_TAG,
 	DMI_STRING_MAX,
 };