Solaris x86 booting sequence

I was confused a bit on the booting sequence, and what each bit does, so I thought I'd write up a quickie here, on my observations. I do not work for Sun, I have no inside knowlege, but this is what I see.

#1: Boot selector

If you have multiple partitions, the boot loader will probably come up and ask you which partition you want to boot. Hopefully that is clear enough. If you dont have multiple partitions on your boot disk, you will go straight into solaris. Or rather, the DCA, then solaris. Note that you can theoretically change the timout by editing /boot/solaris/strap.rc

#2: Device configuration assistant (DCA)

[If you need to download a DCA floppy, get it from sun's DCA page]

This will ask you to press ESC if you want to change device configuration, or where you want to boot from. This is to make up for the fact that x86 machines don't have a nice OpenBOOT chip to sort out REAL "Plug & Play". If you want to skip the 5 second countdown for the DCA, just press ENTER when the count starts, and it will go straight to the next phase of booting.

In solaris 2.6, the Device Assistant seems to set up certain things in /platform/i86pc/boot. This is so the "real" OS has some common format to examine for devices, instead of having lots of nasty x86 hardware specific stuff. That way, Sun can keep the main OS somewhat hardware independant, and keep it very close to the Sparc version.

Under Solaris 8, the DCA is under /boot. It MAY be its own separate fdisk partition, of type "X86BOOT". This could let you have the initial bootpartition on your "main" disk, but boot solaris from a completely different disk. Once the OS is loaded, either way, it will be resident under /boot.

If you ever have to recreate a separate X86BOOT partition... you're in trouble. The best way to do this so far, is to do a fake solaris install onto either a separate disk, or to your swap slice (PRESERVEing everything else!!) and it should get rebuilt for you. If not, you probably have to delete the old data in there first.

The "DCA" can actually been of assistance in sorting out what devices you have. If you select "partial scan", then "Device tasks", and then "View/Edit Devices", it will tell you what solaris THINKS your devices are, and where they are at. Quite useful, when solaris gets completely lost, and you're wondering if it's your fault, or what.

Otherwise, it can give you a warm fuzzy feeling, if you select "Full Scan", and you see all your devices properly recognized.

Note: Seeing a generic name like "disk controller" does **not** mean your device was properly recognized. Only if you see a specific model name is it fully recognized.

#3: OS Boot

Well, actually, the "Boot interpreter". This part seems to be close, but not identical, to the sparc "OpenBoot" 'boot' command. The main differences I notice being:

  • It's "b -r", not "boot -r", if you want to force reconfiguration
  • You don't have nice device aliases like you do with sparc hardware that being said, if you do nothing, it should autoboot into the actual OS in a few seconds. Or you can type something quickly within 5 seconds, and force a "reconfiguration boot", as mentioned earlier.

    Why would you want to do that? Well. sometimes, if your devices have changed a LITTLE, you might want to do this, rather than wade through the whole DCA scan process.

    The "Device Assistant" looks for major changes, like adding or removing a card. However, if, say, you add another disk drive, you'll probably want to just do "b -r", since your disk controller is already recognized. Note that the Device Assistant will itself trigger a silent equivalent of "b -r", after it has detected hardware changes.

    #4: Main OS

    You made it! (I hope)
    Hopefully, you should now see a line with "SunOS5.8" or something in it, and a little twirly text spinner starting. You are now really in the true Solaris environment. From here on in, your experience is almost identical to your brethen who get to work with sparc equipment.

    Until something goes wrong with your hardware. Sigh...

    For more details on boot, and options you can give at stage 3, "man boot" will give you more grungy details.

    Written by: Philip Brown
    Solaris Top