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Monday November 14, 2005

Disabling toxic drivers

Unfortunately all code is not perfect. Even drivers (particularly ones under development) can on occasion have problems that may wedge a specific system during boot. Back in the days of the DCA (provided it wasn't the real-mode driver that was hanging), one could edit the fake prom-tree and keep such drivers from binding.

Equivalent functionality does exist post new-boot. It's however not officially documented yet as the syntax may still change a little as there currently is no way to only disable a specific instance. It currently (snv_28, s10u1_18) uses the generic -B property passing mechanism. A all instances of a driver are disabled by setting disable- to true. The -B option is just another kernel option, and is easily set at boot time by typing 'e' in the GRUB menu, select the kernel line, hit 'e' again and add whatever options to the end of the line, hit enter and 'b' to boot.

So to disable both sd and usbms, one would boot with a kernel line like this:

 
kernel /platform/i86pc/multiboot -B disable-sd=true,disable-usbms=true 

This will cause no instances of either driver to bind. This gives the system a chance to boot, allowing a less buggy driver to be installed, or toxic features to be disabled.