adp94xx kernel driver for linux

Had to install Debian Sarge on a IBM xSeries 306m. This machine comes with a adaptec 9405 SAS controller, which is not yet in the kernel source tree. There are rpms for redhat and SUSE available though, as well as the driver source code, so you can compile it yourself. Steps to add it to the kernel source tree:

-Create a subdir in drivers/scsi called adp94xx
-copy the source files (.h, .c, and Makefile) provided by adaptec into this directory
-add this directory to the top level Makefile in the scsi directory, basing the format on the aic7xxx stuff
-add a line to Kconfig so that menuconfig would pick it up

One question: at what point do you use 'patch' to modify the kernel source tree as opposed to e.g., just sticking in a driver? Is a patch just a way of more conveniently and consistently adding the same thing (as well as distributing it)?

This enabled me to compile it into the kernel, which avoids the necessity of using an initrd to boot the system, since the rootfs will be on a disk attached to that controller. The other alternative is to compile it as a module (haven't yet tried this), or use the binary (rpm) modules supplied by Adaptec. As I was using Debian, I couldn't use the rpms directly, so I converted them into .deb files with Alien, and then extracted them using dpkg -x to get a .ko. One problem I have had with using the driver compiled into the kernel is not being able to get the driver to see the controller when it is configured in RAID mode. The driver defaults to non-RAID mode, which can be switched to RAID mode by sending it a parameter at boot. From reading Documentation/kernel-parameters.txt, and the documentation supplied with the driver, I figured this would be:

adp94xx.adp94xx=attach_HostRAID=1

so I added this at boot by editing the grub boot line. However, it failed to see the controller, reporting:

"Probing AIC-94xx Controller(s)...
AIC-94xx controller(s) attached = 0."


I have got it to work fine when using the driver as a module on a generic Debian 2.6.8 kernel:

modprobe adp94xx adp94xx=attach_HostRAID=1

scsi1 : Adaptec AIC-9405W SAS/SATA Host Adapter
Vendor: IBM-ESXS Model GNA073C33ESTT0Z N Rev: BHOD
Type: Direct-Access
etc
AIC-94xx controller(s) attached = 1.

(also need to modprobe sd-mod so that there is a scsi transport layer so you can access the disk.)

My next attempt will be to change the line in the source code that makes the default to be off:

From adp94xx_osm.c:

/* By default we do not attach to HostRAID enabled controllers.
* You can turn this on by passing
* adp94xx=attach_HostRAID:1
* to the driver (kernel command line, module parameter line).
*/
static int asd_attach_HostRAID = 0;

to

static int asd_attach_HostRAID = 1;

I'll try this when I have more time.

UPDATE: I have tried the above, using a debian 2.6.8 sarge kernel source tree, and compiled it in to the kernel and as a module. It fails to detect the card when it is configured as RAID in the BIOS. I have tried passing it the option on the command line to set this, despite the default supposedly being '1' (modprobe adp94xx adp94xx=attach_HostRAID=1) when used as a module. The only other option I can think of right now is to install the OS on a USB disk (they are 1RU servers with no space for further internal storage). I have tried putting a single disk in and marking this disk as 'simple storage' in the BIOS of the controller which allows data migration, but this still requires RAID as enabled, and it forgets this if you disable RAID