Date: Thu, 22 Mar 2018 11:06:24 -0700 From: Benno Rice <benno@FreeBSD.org> To: FreeBSD Current <freebsd-current@freebsd.org>, freebsd-hackers@freebsd.org Subject: Testing requested: Hybrid ISO/USB boot Message-ID: <D606FA1E-8E53-4D57-8A3C-2914B92385D6@FreeBSD.org>
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Hello all! I=E2=80=99ve 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=E2=80=99ll 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=E2=80=99t 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 =E2=80=9Cbootonly=E2=80=9D 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=E2=80=99ve tested this image under qemu and VMware under all four of = the BIOS/UEFI and CD/HDD combinations. I=E2=80=99ve also booted a system = build around an Asus X399 Prime motherboard with this dd=E2=80=99ed to a = USB stick. I=E2=80=99d love some testing on more systems, especially = things that are more likely to have more customized boot firmwares = (I=E2=80=99m thinking Dell, HP, etc). Many thanks, Benno.=
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