Grokking miniroot.kmod etc.

[Hubert Feyrer <hubert%feyrer.de@localhost>]

Hi Andy,

I'm trying to understand how the new world order works WRT loading a 
ramdisk from the boot loader, in order to update g4u.

My understanding of the previous system is:
 * we make a ramdisk image (ramdisk.fs) e.g. from
   src/distrib/i386/ramdisks
 * we make a kernel that has options MEMORY_DISK_HOOKS and
   MEMORY_DISK_IS_ROOT (and possibly MEMORY_DISK_ROOT_SIZE)
 * we put the ramdisk image into the kernel with mdsetimage,
   and get a kernel that has the ramdisk
 * we then use the regular boot loader to load the kernel and
   use the ramdisk image as root filesystem

Now with the new world order, I see a number of bits that I can't fit 
together:
 * we build a ramdisk image from e.g. src/distrib/i386/ramdisks as
   before
 * There's src/sys/modules/miniroot which builds/installs e.g.
   /stand/i386/4.99.72/modules/miniroot/miniroot.kmod, but it seems
   unrelated to the ramdisk image. Is that correct? What's this
   needed for, at all?
 * for the kernel, I guess the MEMORY_DISK_HOOKS kernel option is still
   needed, but instead of MEMORY_DISK_IS_ROOT and esp.
   MEMORY_DISK_ROOT_SIZE, MEMORY_DISK_DYNAMIC is needed. Does that make
   sense?
 * Now, how to fit things together? Where does the ramdisk image come
   into play?
 * How to tell the bootloader to load the ramdisk after the kernel?
   My guess this is done via boot.cfg - is there an example?
   What is the /ramdisk.kmod mentioned in boot.cfg.4, is it the
   ramdiskbin.fs? Where exactly is this put?

Thanks!


 - Hubert