mfi(4) for fun and profit

Just a day or two ago damien@ committed wpi(4) for the new Intel wireless chips. However, todays story is that marco@ finished getting mfi(4) working as a storage controller. This week is a good week for purdy code.

mfi(4) (short for MegaRAID Firmware Interface) is a driver supporting LSI Logics new RAID controllers for SAS disks. They seem to be the successor for my dearly beloved ami(4) family of controllers with all their speed plus some, but without the warts.

I'm really tempted to go into technical details about why mfi and its hardware is really cool, but I'm going to refrain and just ask you to trust me on this. However, I will say that the people who designed this hardware did an awesome job which is definitely reflected by the code. They've removed the need for a lot of cruft that is necessary in ami, while providing a simpler interface for talking to the hardware.

So far mfi only supports use of the logical disks, but it will be improved upon to add support for the pass through buses, bio/bioctl, and sensors for the state of the disks. All without a vendor provided stack.

For those of you like me who want something to ooh and aah over, here's the dmesg output you get with an mfi plugged in:

mfi0 at pci8 dev 14 function 0 "Dell PERC SAS" rev 0x00, Dell PERC 5/i: irq 5
mfi0: logical drives 2 version 5.0.1-0030 RAM 256MB
scsibus3 at mfi0: 2 targets
sd1 at scsibus3 targ 0 lun 0: SCSI5 0/direct fixed
sd1: 34432MB, 34432 cyl, 64 head, 32 sec, 512 bytes/sec, 70516736 sec total
sd2 at scsibus3 targ 1 lun 0: SCSI5 0/direct fixed
sd2: 16896MB, 16896 cyl, 64 head, 32 sec, 512 bytes/sec, 34603008 sec total