From: Larry Finger Date: Fri, 25 Apr 2008 14:04:32 +0000 (+0200) Subject: Extend README file. X-Git-Tag: b43-fwcutter-013~60 X-Git-Url: https://jxself.org/git/?a=commitdiff_plain;h=e253c5e35935104d42ad8747ab998fdf330f5a88;p=b43-tools.git Extend README file. --- diff --git a/ssb_sprom/README b/ssb_sprom/README index f1c2edf..6f7d7de 100644 --- a/ssb_sprom/README +++ b/ssb_sprom/README @@ -13,3 +13,104 @@ Requirements ------------ 1) C99 compatible compiler. + + +Usage +----- + +The contents of the sprom are exposed to the user in sysfs. This +tool can, in principle, read and write the sprom in place; however, +making a mistake during sprom writing could render your device +unusable. For this reason, we recommend copying the sprom contents +to disk as the first step. This copy can then be modified until it +contains the desired new information. Only then and with caution +should the sprom be rewritten. DO NOT MAKE ANY CHANGES UNLESS YOU +KNOW WHAT YOU ARE DOING!!!! You have been warned!!! + +Obtaining a disk copy of the sprom contents +------------------------------------------- + +This file name 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 and check the path for the +sprom file: + +SSB_SPROM=$(find /sys -name ssb_sprom) +echo $SSB_SPROM + +If the echo command only results in a single instance of "/sys/...", +you may proceed. For systems with more than one SSB-based interface, +there will be such a string for each, and the command that sets the +SSB_SPROM symbol will have to be changed. In the name above, the +sequence states that this device is attached to the 0'th PCI bus via +bridge 0d.0 and is device 04:00.0 on that bridge. To find which of +your SSB devices to select, use the 'lspci -v' command. On my system, +the first line of such output for my interface is "04:00.0 Network +controller: Broadcom Corporation BCM94311MCG wlan mini-PCI (rev 02)". +To select only this device, one would use + +SSB_SPROM=$(find /sys -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 + +Modifying the contents of the working copy +------------------------------------------ + +You may now see 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 + +ssb-sprom -i new_ssb_sprom_copy -P + +to check the contents. + +Rewriting the sprom contents +---------------------------- + +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 + +Once again, you are urged to be absolutely certain of the contents +of the working copy BEFORE taking this step. 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.