Mailing List Archive

embedded fs access?, was Re: Booting ISOs
Hello, my name is Douglas McClendon. I just joined this list. The
question that prompted me to join, is actually quite timely, as it
related to the Booting ISOs thread, which unfortunately, I can't just
continue.

I think the answer the "Booting ISOs" question got, regarding the
knoppix cheatcode, was relevant, but not quite optimal.

Unless I am misunderstanding, using the knoppix cheatcode, requires that
the user duplicate the initramfs and kernel, *outside* the iso image, so
that isolinux will have access to it. I.e. they(knoppix) just put
support in their initramfs to deal with the .iso in the vfat filesystem.

What would be ideal, and what I would *really like*, is if sys/isolinux
would support referencing kernels and initrds that live *within* a .iso
image, that is either residing on a vfat fs on a usbstick, or a .iso
image that is residing in the iso9660 filesystem of the cdrom boot media.

One perhaps controversial use-case of this, would be to take a Fedora
LiveCD iso image, and redistribute it *intact and unmodified* inside
another iso9660 filesystem, along with custom modifications, and a
bootloader that can *efficiently* utilize the kernel inside the
'embedded' iso filesystem, rather than duplicating those bits in the
primary iso filesystem. (and then boot the embedded LiveCD, but adding
the custom patches immediately, before transferring control to the
normal boot scripts)

I believe this could be implemented in a fairly elegant way in syslinux,
and would actually be useful in a multitude of situations.

If I were to start to invest the time, I'd start looking at the isodump
utilitity which now appears to be able to dump the bits from a
particular file from an iso image specified by path. Then try to glue
that code into isolinux so that it could dump the bits of the kernel and
the initrd into memory from the embedded iso image, rather than
reading them from the primary iso9660 (or vfat) filesystem.

I guess my best hope with this message is to inspire someone to do the
work for me. The next best hope would I guess be comments off the top
of peoples heads as to gotchas to expect during implementation, or
otherwise supportive or intelligently critical advice.

Thanks,

-dmc

_______________________________________________
SYSLINUX mailing list
Submissions to SYSLINUX@zytor.com
Unsubscribe or set options at:
http://www.zytor.com/mailman/listinfo/syslinux
Please do not send private replies to mailing list traffic.
Re: embedded fs access?, was Re: Booting ISOs [ In reply to ]
Douglas McClendon wrote:
> I believe this could be implemented in a fairly elegant way in syslinux,
> and would actually be useful in a multitude of situations.
>
> If I were to start to invest the time, I'd start looking at the isodump
> utilitity which now appears to be able to dump the bits from a
> particular file from an iso image specified by path.
I stumbled across this some days ago,
http://www.mgerards.net/blog/?cat=4

He writes about booting from iso9660 using a "loopback" module in grub2,
and the dist he is using is based on debian. A hot on the plate
packaged debian unstable, its called sidux. Docs about the fromiso
cheatcode:
http://manual.sidux.com/en/hd-install-opts-en.htm

Maybe it is possible to build something similar with a c32 program ?

Regards
Peter

--

/bitrunner/

*0708-460260*
Andra LĂ„nggatan 28
41327 Göteborg
Sweden

_______________________________________________
SYSLINUX mailing list
Submissions to SYSLINUX@zytor.com
Unsubscribe or set options at:
http://www.zytor.com/mailman/listinfo/syslinux
Please do not send private replies to mailing list traffic.
Re: embedded fs access?, was Re: Booting ISOs [ In reply to ]
Peter wrote:
> I stumbled across this some days ago,
> http://www.mgerards.net/blog/?cat=4
>
> He writes about booting from iso9660 using a "loopback" module in grub2,
> and the dist he is using is based on debian. A hot on the plate
> packaged debian unstable, its called sidux. Docs about the fromiso
> cheatcode:
> http://manual.sidux.com/en/hd-install-opts-en.htm
>
> Maybe it is possible to build something similar with a c32 program ?

That should definitely be possible.

-hpa

_______________________________________________
SYSLINUX mailing list
Submissions to SYSLINUX@zytor.com
Unsubscribe or set options at:
http://www.zytor.com/mailman/listinfo/syslinux
Please do not send private replies to mailing list traffic.
Re: embedded fs access?, was Re: Booting ISOs [ In reply to ]
Peter wrote:
> Douglas McClendon wrote:
>> I believe this could be implemented in a fairly elegant way in syslinux,
>> and would actually be useful in a multitude of situations.
>>
>> If I were to start to invest the time, I'd start looking at the isodump
>> utilitity which now appears to be able to dump the bits from a
>> particular file from an iso image specified by path.
> I stumbled across this some days ago,
> http://www.mgerards.net/blog/?cat=4
>
> He writes about booting from iso9660 using a "loopback" module in grub2,
> and the dist he is using is based on debian. A hot on the plate
> packaged debian unstable, its called sidux. Docs about the fromiso
> cheatcode:
> http://manual.sidux.com/en/hd-install-opts-en.htm
>
> Maybe it is possible to build something similar with a c32 program ?


Thanks! The first link and the availability of the grub loopback
feature was definitely news to me. I have used grub in the past to boot
custom fedora livecds, though moved to isolinux following the lead of
the official fedora livecds. While grub may have some disadvantages, it
is pretty cool to know that I can use it already to implement a
proof-of-concept of what I described, while waiting for myself or
someone else to implement the same sort of thing in sys/isolinux.

The second link was also good for reference, though I already know the
guts of all the initramfs issues that will be involved.

Thanks also hpa for confirming that the c32 would be the way to go,
should I embark on the task. Most likely I won't find the time in the
near-term future, but maybe someday.

-dmc

_______________________________________________
SYSLINUX mailing list
Submissions to SYSLINUX@zytor.com
Unsubscribe or set options at:
http://www.zytor.com/mailman/listinfo/syslinux
Please do not send private replies to mailing list traffic.