This article is from a FAQ concerning SCO operating systems. While some of the information may be applicable to any OS, or any Unix or Linux OS, it may be specific to SCO Xenix, Open There is lots of Linux, Mac OS X and general Unix info elsewhere on this site: Search this site is the best way to find anything.
This applies to at least 3.2v4.0 and later. As always, make and verify a backup and a set of emergency diskettes before any major system surgery.
Make sure that the appropriate driver is already installed. It may already be there, or it may be in the form of a BTLD. Your manual should provide the instructions for this step.
The file /etc/conf/cf.d/mscsi contains a list of SCSI devices and the parameters (such as which host adapter, what SCSI ID they are, etc.) required for them. The safest change to make is to replace the name of the old adapter driver (e.g. ad for an Adaptec 154x) to the name of the new one (e.g. arad for an AIC-7770-based adapter) on each such line. There is another option, which is to use auto. I am not sure exactly how this works if there is more than one host adapter installed, so on systems with multiple host adapters it is probably wisest to list the specific host adapter rather than using auto.
In /etc/conf/sdevice.d you will find files named after the drivers you're installing and removing (e.g. ad and arad). You will need to edit each of them. The second column should be set to Y for a driver which is enabled, and N for a driver which is not. For some drivers, you will also need to edit the adapter address in columns 7 and 8; many adapters do not require this. There is no need to change /etc/conf/cf.d/sdevice, as it is built from these files when you relink the kernel.
There's at least one special case which deserves to be noted here. If you are moving from an EISA host adapter to a PCI one, you may need to enable PCI support in your kernel if this is the first PCI device. In /etc/conf/sdevice.d/pci, you should see a line which begins pci N. Change the N to Y. If you are removing your last EISA device, you may wish to do the inverse in /etc/conf/sdevice.d/eisarom with the eisarom line, though it probably doesn't hurt to have this support in the kernel even though you have no EISA devices. This also applies to other hardware changes involving addition or deletion of PCI and EISA devices, and it applies in reverse if you're removing your last PCI device and adding your first EISA one.
Relink the kernel, shut down, and swap the hardware.
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