README and FAQ for the fla driver. ================================== [0] COPYRIGHT & LICENSE Please read the COPYRIGHT file carefully. If you cannot agree to be bound by the terms of this license, please contact M-systems and make arrangements with them. [1] What does this driver do ? This driver supports up to eight M-systems DiskOnChip devices. The driver has been tested with the following devices: DiskOnChip2000 (8, 12, 24, 32, 40, 72, 144 MB) DiskOnChipMillenium (8 MB) DiskOnChipMillenium TSOP (8 MB) You can find full details, specs etc on M-systems homepage: http://www.m-sys.com [2] Which firmware version ? The driver has only been tested with version 1.21. [3] How many devices ? The driver supports up to 8 devices but have been tested only with 5 due to hardware limitations in my test setup. [4] Which FreeBSD versions ? The driver is tested for 4.0-CURRENT and 3.3-RELEASE. Porting to earlier versions of FreeBSD should be a simple matter of modifying the fla.c file. [patches are welcome] [5] Can I install FreeBSD with sysinstall ? Yes, it has been tested in FreeBSD-4.0-CURRENT and it works. You will need to build a kernel with the fla driver since the default "GENERIC" kernel doesn't contain the fla driver. [6] How to boot from a fla device ? FreeBSD 4.0 and forward find their root device by reading the /etc/fstab, so the DiskOnChip devices will work just like any other device. Earlier FreeBSD kernels recognizes the root device using various hacks. These hacks doesn't recognize the fla device so some "real" hacks are needed to boot from your fla device. In pre 4.0 versions specifying the boot device in the kernel config file this way is the easiest way to do it: config kernel root on major 28 minor 65538 [7] How to disklabel a fla device ? Look at the script in prep.fla.sh, it will do the job for you. [8] Who to contact ? doc2k@phk.freebsd.dk will offer limited best-effort help to the extent time permits. Further support for special projects or configurations available at reasonable hourly rates. [9] Getting detailed The DiskOnChip product gets out in some odd corners of the PC-architecture, and chances are that things don't do what you expect. Here are some hints and random observations I've made during my work with these devices. [9a] Choosing an address for the DOC Each DOC needs a 8K memory window starting on an 8K boundary. The lowest possible address is C000:0, the highest is DE00:0 If your hardware puts the DOC another place, you will need to modify the doc2k_probe() call in fla.c. It is important that you set the BIOS to not do "fancy things" with this window, in particular no kind of cache or shadowing can be enabled. Be aware that some hardware will decode a 32k memory window for the DOC device. If everything is OK, the DOC will print a message during the BIOS startup. For large devices it can take some time to check the flash data structures, but if it takes more than 3 minutes something is wrong. If you boot a MSDOS floppy and run FDISK you should be able to see the DOC device. If it doesnt work: If you machine never gets to the point where it will boot, but just hangs it could be because you have a BIOS which need the "slightly special" DOC firmware. Obviously you will need to put the DOC in another machine to load this firmware. You can download the firmware and utilities from M-systems website http://www.m-sys.com If the machine boots, but the device isn't visible it can be because some other device uses the same memory window, or because the BIOS prevents it from being used. If you boot MSDOS and enter DEBUG, you should be able to find a BIOS extension signature at the address using the 'd' command, for instance 'd d800:0'. A special case is when the DOC prints the BIOS message but disappears afterwards, this can happen because another card (NCR SCSI controllers for instance) steal the memory window later in the boot process. In such a case the above check with DEBUG will not show the BIOS signature. [9b] So just who is drive 'C' here anyway ? Using the DUPDATE program you can choose to have the DOC add itself at the front or the back of the device list. This is, unfortunately not the only thing affecting the drive order, the above mentioned NCR SCSI controllers also have some builtin AI, and the result can be very confusing because the DOC will come before even the floppy as a result. There is no simple solution for this case, only variuos work-arounds. But chances are good that most users will not use both a DOC and a SCSI in the same system, except maybe for initial programming. [9c] MBR/fdisk The boot firmware in the DOC and/or the FreeBSD bootblocks mandate that the first MBR slice/(partition in FDISK lingo) start exactly at "sector #1, head #1, cylinder #0." You will have problems booting from the fla if you don't get this right. The prep.fla.sh script will do this for you. DO NOT WRITE JUNK IN THE MBR! The DOC firmware relies on various fields and can get utterly confused if they don't make sense. [9d] Getting the FreeBSD kernel to use the fla as root Please see above under item 6. [9e] I turned the machine off while it was running and now my DOC hangs during boot/panics the machine/does weird things. If a write operation to the DOC gets interrupted by reset or power-failure, it can happen that the flash data structures are left in a state the sofware cannot cope with. Your best chance is to DUPDATE, DFORMAT the device again. If it hangs during boot, you can use this particular dirty trick ENTIRELY AT YOUR OWN RISK! DO NOT COMPLAIN IF THIS DOESN'T WORK FOR YOU OR IF YOU DESTROY YOUR COMPUTER OR DOC DEVICE DOING IT! Jumper the DOC for an address which will not work, but which will not interfere with the system either, C000:0 seems to work pretty universally for this. Boot MSDOS and rejumper the DOC for its real (working) address. Run DUPDATE and use the /win:xxxx argument to point it at the DOC device. [9f] Apart from that... ...the DOC is just like any other disk, but it is silent, has better MTBF and doesn't take up a lot of space. [10] History The fla driver was written by Poul-Henning Kamp under contract for M-systems, and using their "OSAK" development kit. Good Luck, Poul-Henning $FreeBSD$