Linux Wireless

This page contains info for developers, not really useful for end users.

Earlier we were using other, older firmwares. The table contains all drivers supported by fwcutter.

bcm43xx is the old deprecated driver. It uses the ieee80211 + softmac libraries of code shared with other drivers. This stack is deprecated and being replaced by the new mac80211 stack. A new stack implies brand new, re-written driver(s): b43 and b43legacy.

• ssb-sprom
• * A tool for the modification of the Broadcom Sonics Silicon Backplane SPROM (e.g. you can permanently change the MAC address or the PCI IDs of your wireless card – useful on some (e.g. Compaq/HP) laptops where the BIOS checks these at boot. It's now part of b43-tools:

git clone git://git.bues.ch/b43-tools.git

• * To use the sprom tool, it is necessary to get a disk copy of your sprom from the /sys file system. The file path for the sprom contents depends on the bus layout of the specific computer being used and will be something like

  /sys/devices/pci0000:00/0000:00:0d.0/0000:04:00.0/ssb_sprom

• * It is not recommended that you try to type the name. Instead, you should use the following commands to get the working copy:

  SSB_SPROM=$(find /sys/devices -name ssb_sprom)
  echo $SSB_SPROM

• * If the echo command only results in a single instance of “/sys/…”, you may proceed. For systems with more than one SSB-based interface, there will be such a string for each, and the command that sets the SSB_SPROM symbol will have to be changed. In the name above, the sequence states that this device is attached to the 0'th PCI bus via bridge 0d.0 and is device 04:00.0 on that bridge. To find which of your SSB devices to select, use the 'lspci -v' command. On my system, the first line of such output for my interface is “04:00.0 Network controller: Broadcom Corporation BCM94311MCG wlan mini-PCI (rev 02)”. For this device, one would use

  SSB_SPROM=$(find /sys/devices -name ssb_sprom | grep 04:00.0)
  echo $SSB_SPROM

• * Of course, the “04:00.0” needs to match your system, and check the output value to determine that there is now a single instance of “/sys…” and that the path matches the device whose SPROM is to be changed. If not, adjust the string after 'grep' accordingly.
• * Once the SSB_SPROM variable matches the path to ssb_sprom for your device, get a working copy of the sprom contents with

  sudo cat $SSB_SPROM > ssb_sprom_copy

• * You may now look at the contents of your sprom with the command

  ssb-sprom -i ssb_sprom_copy -P

• * As an example, let us suppose that you have purchased a Dell mini-pci card to use in an HP laptop. The HP BIOS refuses to use the card when the pcivendor is Dell (code 0x1028), not HP (code 0x103C). From the information provided by an “ssb-prom –help” command, we learn that the switch needed to change this vendor code is “–subv”. To change that code, we use the command

  ssb-sprom -i ssb_sprom_copy -o new_ssb_sprom_copy --subv 0x103C

• * to write the HP vendor ID to our working copy. I use different input and output files so as not to destroy the original. If further changes are needed, for example the PCI product ID, the command

  ssb-sprom -i new_ssb_sprom_copy -o new_ssb_sprom_copy --subp 0x137C

• * would be used. Note that the input and output files may be the same.
• * Once you think you have updated correctly, use the following to check the contents:

  ssb-sprom -i ssb_sprom_copy -P

• * Once the sprom contents are the way you want them, and presumably correct, you are ready to rewrite the file. First, use

  echo $SSB_SPROM

• * to ensure that this symbol still contains the SPROM path. If not, then it will have to be reloaded as discussed above.
• * You are then ready to rewrite the sprom with

  sudo cp new_ssb_sprom_copy $SSB_SPROM

• * IMPORTANT: The 2.6.32 kernel will throw the following error message and refuse to write the SPROM:

SPROM write: Could not freeze devices. No suspend support. Is CONFIG_PM enabled?

• * Apply the following patch to the 2.6.32 kernel to allow programming the SPROM on that kernel. Alternatively install a newer or an older kernel.

http://marc.info/?l=linux-wireless&m=125900356410309&q=raw

• * Once again, you are urged to be absolutely certain of the contents of the working copy BEFORE writing it to hardware. If your interface becomes unusable as a result of writing incorrect data into the sprom, the responsibility is YOURS. Once again, you have been warned.
• * A firmware assembler/disassembler can be found in the git repository at
• * *

  git clone git://git.bues.ch/b43-tools.git

• * There are more development and debugging tools available in the b43-tools git repository. Just clone it and read the shipped documentation files.
• * *

  git clone git://git.bues.ch/b43-tools.git

A mirror of the b43-tools GIT repository (git:git.bues.ch/b43-tools.git) can be found on github: https://github.com/mbuesch/b43-tools