Does the bootprompt command "pci=irqmask=" command work with the 2.4.21 kernel and later versions or is it obsolete?

I've tried at boot up to add the command pci=irqmask=0x0e00 to force the kernel to assign IRQ 9, 10 and 11 and no other IRQ to the PCI devices (thereby making sure that IRQ 15 that I need for an ISA device is not occupied) on my system (SuSE Linux 9.0 and the 2.4.21 Linux kernel). The kernel doesn't seem to care about this argument though and therefore I came to wonder if this is an old and obsolete command?

Many thanks
/Peso

Another question regarding this command...

This command can and should be used at the boot prompt at start-up of the system, right? You don't have to do it during installation of the system?

The reason I ask is that I've tried to force the kernel to use a couple of IRQs for the PCI devices during start-up, but the kernel doesn't seem to care if I issue this command at boot time or not, it still assigns whatever IRQs it wants to the PCI devices. In my BIOS I've reserved a couple of IRQs for ISA devices, but I know that at start-up Linux rescans the PCI devices on the system and maybe (I would be happy if someone could tell me if this is the case or not!!) it reassigns IRQs as well and overrides the settings in BIOS?

Many thanks
/Peso