Re: Root device independent bootable disk images

[christos%astron.com@localhost (Christos Zoulas)]

In article <23569.9846.9159.416183%guava.gson.org@localhost>,
Andreas Gustafsson  <gson%gson.org@localhost> wrote:
>Hi all,
>
>Since jmcneill's commit of src/lib/libutil/getfsspecname.c 1.5, NetBSD
>supports the special string "ROOT." as an alias for the root device in
>/etc/fstab.  This can be used to avoid hard-coding the device name of
>the root disk on bootable disk images, allowing a single image to be
>booted from disks having different device names.
>
>This feature is currently used by the ARM images, but not by the
>images for other architectures.  I would like to change this.  My
>immediate motivation for this is to fix PR 51503, "7.0.1/amd64 USB
>install image root mount fails when sd present", but I belive it would
>also be useful on live images as well as install images, and on
>other architectures.  Note that I am not proposing changing the fstab
>that gets written to the target disk when installing a system using
>sysinst, only that of pre-built disk images such as those from
>"build.sh install-image" or "build.sh live-image".
>
>The question is, is there any reason to keep the existing machinery
>for specifying a fixed device name via the BOOTDISK make variable?
>Or in other words, can anyone think of an architecture or type of disk
>image where the "ROOT." reference might not work, or where a
>hard-coded root disk device in /etc/fstab might otherwise be
>desirable?
>
>If not, the change I'm proposing would basically amount to changing
>"/dev/@@BOOTDISK@@" to "ROOT." in src/distrib/common/bootimage/fstab.in
>and fstab.install.in, followed by a bunch of cleanup work to remove
>things that are no longer used or needed, such as all references to
>BOOTDISK in the Makefiles.
>
>The "build.sh live-image" target currently builds two live images each
>for i386 and amd64, with names containing "-wd0root" and "-sd0root",
>respectively.  With the proposed change, these would become almost
>identical, differing only in size and the OMIT_SWAPIMG setting, and
>probably ought to be merged into one.  Other architectures only have
>at most a single live image each, but their names also contain strings
>like "-sd0root" or "-ra0root" that would now be meaningless and should
>be removed.
>
>Comments?  Objections?

I think this is a good idea!

christos