svn commit: r253513 - head/release

[Teske, Devin]

On Jul 21, 2013, at 6:39 AM, Alexey Dokuchaev wrote:

> On Sun, Jul 21, 2013 at 05:23:34AM +0000, Glen Barber wrote:
>> New Revision: 253513
>> URL: http://svnweb.freebsd.org/changeset/base/253513
>> 
>> Log:
>>  Create memstick images with the '.img' filename extension.
>> 
>>  Requested by:	many
>>  [...]
> 
> Is there any work being done to merge the .iso and .img into single,
> hybrid bootable image (c.g. Haiku)?

I wonder how Haiku does it.

I use ISOLINUX (part of the SYSLINUX family) as my boot loader.

The ISO9660 layer boots ISOLINUX and then chain-loads the mfsroot, displaying my beastie Forth menu.

Then from the mfsroot boot environment, sysinstall runs /install.cfg:

http://druidbsd.cvs.sourceforge.net/viewvc/druidbsd/druidbsd/druid/dep/freebsd/mfsroot/standard/src/install.cfg?revision=1.1&view=markup

 which runs a small script:

http://druidbsd.cvs.sourceforge.net/viewvc/druidbsd/druidbsd/druid/dep/freebsd/mfsroot/standard/src/fis/load_menu?revision=1.1&view=markup

Which looks for /dev/iso9660/VOL_ID

Where VOL_ID is set by the mkisofs(8) `-V VOL_ID'  flag when producing the boot media. See "BOOT_VOLID" in my GNUMakefile that calls mkisofs(8):

http://druidbsd.cvs.sourceforge.net/viewvc/druidbsd/druidbsd/druid/GNUmakefile.in?revision=1.7&view=markup

Now here's the trick...

It doesn't matter whether you burned the ISO to a CD/DVD or you imaged it to a USB Thumb...

... phk's GEOM layer picks up and creates /dev/iso9660/VOL_ID regardless of what medium you booted from (so-long as it was an ISO that was post-processed with the ISOLINUX utility "isohybrid").

So in my hybridized installer, I have a bootstrap script that runs before sysinstall that mounts /dev/iso9660/VOL_ID to /cdrom and I end up using /cdrom always.

That's the very basic *gist* of how I achieve hybrid booting for FreeBSD. Of course... that's only the *start*. Of course, to get sysinstall to install from /cdrom, I had to code a new media access module called "mediaSetNullFS":

http://druidbsd.cvs.sourceforge.net/viewvc/druidbsd/druidbsd/druid/dep/freebsd/patches/local_patches/usr.sbin%3A%3Asysinstall%3A%3Anullfs.c.patch?view=markup

Whose job is (when you configure your installation to use this access method) is to take the path given and do a mount_nullfs from point-A to point-B *prior* to doing the chroot into the formatted disk (here, like all media access methods, the point-B is "/dist" within the chroot environment).

Of course... moving forward... we would need to re-apply logistics to bsdinstall to work with ISOLINUX and isohybrid images -- though I gather it would be even easier than making sysinstall work.



>  I've asked this question before,
> but I cannot recall now what was the outcome if it...
> 

Did I answer you last time? Just curious. I've been doing this for a while.
-- 
Devin

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