Testing requested: Hybrid ISO/USB boot

Maurizio Vairani maurizio1018 at gmail.com
Fri Mar 23 12:53:46 UTC 2018

2018-03-22 19:06 GMT+01:00 Benno Rice <benno at freebsd.org>:

> Hello all!
> I’ve been working on the ability to create hybrid ISO/HDD boot images for
> x86, a la what Linux systems do with ISOHYBRID. The general theory seems to
> be that ISO images have a 32KB hunk of zeroes at the front that they
> generally ignore so we’ll stick something in there that can handle booting
> if need be. The cases generally break down as follows:
> UEFI with CD: Boots using an EFI system partition embedded in the ISO
> image. This loads loader, and so on.
> UEFI with HDD: Same as above as UEFI doesn’t really care what the
> underlying medium is and it sees the ISO image.
> Legacy BIOS with CD: Boots using El Torrito as always.
> And now for the new part:
> Legacy BIOS with HDD: Sees a DOS MBR stuck in the 32KB at the front of the
> ISO image. This MBR contains our MBR boot code, which sees an active BSD
> slice containing a variant of our BSD boot code that reads from the ISO
> filesystem instead of UFS. This finds loader in the ISO filesystem and
> loads that. Loader has had support for reading ISO9660 images off HDDs
> added. Everything continues normally after that.
> The review for these changes is here:
> https://reviews.freebsd.org/D14799 <https://reviews.freebsd.org/D14799>
> And a version of the standard “bootonly” ISO image built with these
> changes is here:
> https://people.freebsd.org/~benno/hybrid-bootonly.iso.xz <
> https://people.freebsd.org/~benno/hybrid-bootonly.iso.xz>
> I’ve tested this image under qemu and VMware under all four of the
> BIOS/UEFI and CD/HDD combinations. I’ve also booted a system build around
> an Asus X399 Prime motherboard with this dd’ed to a USB stick. I’d love
> some testing on more systems, especially things that are more likely to
> have more customized boot firmwares (I’m thinking Dell, HP, etc).
> Many thanks,
>         Benno.
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Hi Benno,
thank you for your work.

On a Mac mini "Core i5" 2.3 (Mid-2011), booting via USB, it hangs very
early, after writing:
FreeBSD/x86 bootstrap loader, version 1.1
(Wed Mar 21 10:27:48 PDT 2018 benno at bobthe)


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