While looking into how to look up Debian packages based on hardware
+information, to find the packages that support a given piece of
+hardware, I refreshed my memory regarding modalias values, and decided
+to document the details. Here are my findings so far, also available
+in
+the
+Debian Edu subversion repository:
+
+
Modalias decoded
+
+
This document try to explain what the different types of modalias
+values stands for. It is in part based on information from
+<URL: https://wiki.archlinux.org/index.php/Modalias >,
+<URL: http://unix.stackexchange.com/questions/26132/how-to-assign-usb-driver-to-device >,
+<URL: http://code.metager.de/source/history/linux/stable/scripts/mod/file2alias.c > and
+<URL: http://cvs.savannah.gnu.org/viewvc/dmidecode/dmidecode.c?root=dmidecode&view=markup >.
+
+
The modalias entries for a given Linux machine can be found using
+this shell script:
+
+
+find /sys -name modalias -print0 | xargs -0 cat | sort -u
+
+
+
The supported modalias globs for a given kernel module can be found
+using modinfo:
+
+
+% /sbin/modinfo psmouse | grep alias:
+alias: serio:ty05pr*id*ex*
+alias: serio:ty01pr*id*ex*
+%
+
+
+
PCI subtype
+
+
A typical PCI entry can look like this. This is an Intel Host
+Bridge memory controller:
+
+
+pci:v00008086d00002770sv00001028sd000001ADbc06sc00i00
+
+
+
This represent these values:
+
+
+ v 00008086 (vendor)
+ d 00002770 (device)
+ sv 00001028 (subvendor)
+ sd 000001AD (subdevice)
+ bc 06 (bus class)
+ sc 00 (bus subclass)
+ i 00 (interface)
+
+
+
The vendor/device values are the same values outputted from 'lspci
+-n' as 8086:2770. The bus class/subclass is also shown by lspci as
+0600. The 0600 class is a host bridge. Other useful bus values are
+0300 (VGA compatible card) and 0200 (Ethernet controller).
+
+
Not sure how to figure out the interface value, nor what it
+means.
+
+
USB subtype
+
+
Some typical USB entries can look like this. This is an internal
+USB hub in a laptop:
+
+
+usb:v1D6Bp0001d0206dc09dsc00dp00ic09isc00ip00
+
+
+
Here is the values included in this alias:
+
+
+ v 1D6B (device vendor)
+ p 0001 (device product)
+ d 0206 (bcddevice)
+ dc 09 (device class)
+ dsc 00 (device subclass)
+ dp 00 (device protocol)
+ ic 09 (interface class)
+ isc 00 (interface subclass)
+ ip 00 (interface protocol)
+
+
+
The 0900 device class/subclass means hub. Some times the relevant
+class is in the interface class section. For a simple USB web camera,
+these alias entries show up:
+
+
+usb:v0AC8p3420d5000dcEFdsc02dp01ic01isc01ip00
+
usb:v0AC8p3420d5000dcEFdsc02dp01ic01isc02ip00
+
usb:v0AC8p3420d5000dcEFdsc02dp01ic0Eisc01ip00
+
usb:v0AC8p3420d5000dcEFdsc02dp01ic0Eisc02ip00
+
+
+
Interface class 0E01 is video control, 0E02 is video streaming (aka
+camera), 0101 is audio control device and 0102 is audio streaming (aka
+microphone). Thus this is a camera with microphone included.
+
+
ACPI subtype
+
+
The ACPI type is used for several non-PCI/USB stuff. This is an IR
+receiver in a Thinkpad X40:
+
+
+acpi:IBM0071:PNP0511:
+
+
+
The values between the colons are IDs.
+
+
DMI subtype
+
+
The DMI table contain lots of information about the computer case
+and model. This is an entry for a IBM Thinkpad X40, fetched from
+/sys/devices/virtual/dmi/id/modalias:
+
+
+dmi:bvnIBM:bvr1UETB6WW(1.66):bd06/15/2005:svnIBM:pn2371H4G:pvrThinkPadX40:rvnIBM:rn2371H4G:rvrNotAvailable:cvnIBM:ct10:cvrNotAvailable:
+
+
+
The values present are
+
+
+ bvn IBM (BIOS vendor)
+ bvr 1UETB6WW(1.66) (BIOS version)
+ bd 06/15/2005 (BIOS date)
+ svn IBM (system vendor)
+ pn 2371H4G (product name)
+ pvr ThinkPadX40 (product version)
+ rvn IBM (board vendor)
+ rn 2371H4G (board name)
+ rvr NotAvailable (board version)
+ cvn IBM (chassis vendor)
+ ct 10 (chassis type)
+ cvr NotAvailable (chassis version)
+
+
+
The chassis type 10 is Notebook. Other interesting values can be
+found in the dmidecode source:
+
+
+ 3 Desktop
+ 4 Low Profile Desktop
+ 5 Pizza Box
+ 6 Mini Tower
+ 7 Tower
+ 8 Portable
+ 9 Laptop
+ 10 Notebook
+ 11 Hand Held
+ 12 Docking Station
+ 13 All In One
+ 14 Sub Notebook
+ 15 Space-saving
+ 16 Lunch Box
+ 17 Main Server Chassis
+ 18 Expansion Chassis
+ 19 Sub Chassis
+ 20 Bus Expansion Chassis
+ 21 Peripheral Chassis
+ 22 RAID Chassis
+ 23 Rack Mount Chassis
+ 24 Sealed-case PC
+ 25 Multi-system
+ 26 CompactPCI
+ 27 AdvancedTCA
+ 28 Blade
+ 29 Blade Enclosing
+
+
+
The chassis type values are not always accurately set in the DMI
+table. For example my home server is a tower, but the DMI modalias
+claim it is a desktop.
+
+
SerIO subtype
+
+
This type is used for PS/2 mouse plugs. One example is from my
+test machine:
+
+
+serio:ty01pr00id00ex00
+
+
+
The values present are
+
+
+ ty 01 (type)
+ pr 00 (prototype)
+ id 00 (id)
+ ex 00 (extra)
+
+
+
This type is supported by the psmouse driver. I am not sure what
+the valid values are.
+
+
Other subtypes
+
+
There are heaps of other modalias subtypes according to
+file2alias.c. There is the rest of the list from that source: amba,
+ap, bcma, ccw, css, eisa, hid, i2c, ieee1394, input, ipack, isapnp,
+mdio, of, parisc, pcmcia, platform, scsi, sdio, spi, ssb, vio, virtio,
+vmbus, x86cpu and zorro. I did not spend time documenting all of
+these, as they do not seem relevant for my intended use with mapping
+hardware to packages when new stuff is inserted during run time.
+
+
Looking up kernel modules using modalias values
+
+
To check which kernel modules provide support for a given modalias,
+one can use the following shell script:
+
+
+ for id in $(find /sys -name modalias -print0 | xargs -0 cat | sort -u); do \
+ echo "$id" ; \
+ /sbin/modprobe --show-depends "$id"|sed 's/^/ /' ; \
+ done
+
+
+
The output can look like this (only the first few entries as the
+list is very long on my test machine):
+
+
+ acpi:ACPI0003:
+ insmod /lib/modules/2.6.32-5-686/kernel/drivers/acpi/ac.ko
+ acpi:device:
+ FATAL: Module acpi:device: not found.
+ acpi:IBM0068:
+ insmod /lib/modules/2.6.32-5-686/kernel/drivers/char/nvram.ko
+ insmod /lib/modules/2.6.32-5-686/kernel/drivers/leds/led-class.ko
+ insmod /lib/modules/2.6.32-5-686/kernel/net/rfkill/rfkill.ko
+ insmod /lib/modules/2.6.32-5-686/kernel/drivers/platform/x86/thinkpad_acpi.ko
+ acpi:IBM0071:PNP0511:
+ insmod /lib/modules/2.6.32-5-686/kernel/lib/crc-ccitt.ko
+ insmod /lib/modules/2.6.32-5-686/kernel/net/irda/irda.ko
+ insmod /lib/modules/2.6.32-5-686/kernel/drivers/net/irda/nsc-ircc.ko
+ [...]
+
+
+
If you want to help implementing a system to let us propose what
+packages to install when new hardware is plugged into a Debian
+machine, please send me an email or talk to me on
+#debian-devel.
+
+
Update 2013-01-15: Rewrite "cat $(find ...)" to
+"find ... -print0 | xargs -0 cat" to make sure it handle directories
+in /sys/ with space in them.
+
+
+
+
+
