Difference between revisions of "User:Apple/projects/ISOMetro"

Revision as of 11:42, 22 November 2010

Abstract

Funtoo needs to be able to create bootable media.

Needs? We seem to be doing fine without our own branded media.

Anyway, it shouldn't be hard to add ISO/image generation to Metro.

I should say I get really confuzed when figuring out bootloader->kernel->init, so this might get messy.

The following is some pseudosteps which I think would create an ISO.

1. Create a stage4, but instead of tar compression, use squashfs.
   • From brief exploration, it seems targets/gentoo/stage/capture will be the place to edit.
2. Make an kernel w/ genkernel; should be able to handle squashfs.
   • If not with genkernel, get a generic kernel (monolithic or modular), make initramfs with better-initramfs.
3. Prepare isolinux.
   • ISOLINUX's documentation is a little arcane, and I have no idea how gentoo's livedvd handles EFI.
4. ...
5. Profit!

LiveCD/DVD Generation

Squashfs compression in Metro

Taking a look at etc/builds/funtoo/build.conf, there is no reference to what type to capture (see targets/gentoo/stage/capture/). I have no idea where to specify ami (and therefore any other capture method).

Metro would need to create a stage4, then use that as a seed for an ISO (or, shall we do something completely different?).

Update 1

Metro comes bundled with a stage4 target. The stage4 collects targets/gentoo/stage/capture/tar.spec; some quick edits later it should be squashfs-compressed.

This stage contains a full dev-environment (gcc, portage etc.) which usually doesn't go onto installation media. I like them there, but others may want a way to prune.

Update 2

Apart from fine-tuning init (and pruning), this is pretty much done.

Init

Autodetection, MOTD, autologin all need to be done (currently it boots into a regular login which hasn't been setup).

Waiting for Funtoo Startup to get written.

Bootable kernel

I'm pretty sure a genkernel kernel can be put on a livecd as-is, but by now the squashfs is set in stone; too late for the modules to be placed in /lib/modules.

I seem to remember a gentoo_{or maybe it was ubuntu...} livecd with grub. How?

Update 1

With "stage5", we actually have the kernel and modules inside the squashfs (so no problem there); the problem is now we need it _outside_...

Probably not a major problem. unsquashfs can selectively extract any necessaries from it.

The final part of the process is bringing it altogether. I can't imagine that metro can take a stage5.sqfs and make funtoo-${subarch}.iso.

Update 2

Using a shell script, it can be quite easy to collect the pieces for a livecd. I'm not sure what metro can run after steps/capture, but that might be able to do it at some point after.

isolinux and its config are pretty static on an arch, but I would like to see a dynamic way of creating them.

Other than that, just some init (loads of openrc errors) tweaking.

LiveUSB

Now, this is slightly easier yet more difficult. A liveUSB image should be the product of:

However, boot-loaders (EXTLINUX, GRUB) need a real mounted device, which is $DIFFICULTY; especially when considering automating it: metro can (if your portage snapshot is already made) run many instances at the same time without problem; otherwise you'd need a spare partition and fast drives so you can dd off many images (I suspect it would be several hours per image).

Mounting an empty image via loop and writing to it doesn't work AFAIK:

LVM

Some of us are loud proponents for lvm, and installing a gentoo/funtoo instance on an LVM on a USB has the possibility of being *very* practical.

Basically, instead of the squashfs, we have a (compressed or not) lvm image that we mount as our rootfs in the live environment; the "stage 5" (stage 4 + kernel stuff).

To install it, just dd the lvm to the hdd (as long as the hdd has the capacity to hold the lvm image).

This should put a very small partition onto the hdd with the rest zeroed and unused. In the live environment: fdisk in and change the end cylinder of the partition (max it out), then pvresize to get the lvm filling the disk.

Update 1

Unix's "everything is a file" falls down here (just saying).

Update 2

isolinux's documentation mentions isohybrid, which can make the the same livecd also bootable from keys.

Two updates down, I haven't looked at this yet (LiveCD first).

References

http://edoceo.com/liber/gentoo-live-usb - Unfortunately, in this case, pretty much all of the work has already been done by catalyst.

http://muzso.hu/2009/07/28/how-to-resize-an-lvm-physical-volume-without-a-reboot

tl;dr

I need to brush up on init/openrc.

Usage (testing)

The following block only needs to be run once, the first time you use metro.