Date: Fri, 23 Mar 2018 14:01:39 -0700 From: Benno Rice <benno@FreeBSD.org> To: Thomas Schmitt <scdbackup@gmx.net> Cc: freebsd-hackers@freebsd.org, freebsd-current@freebsd.org Subject: Re: Testing requested: Hybrid ISO/USB boot Message-ID: <35FF5A67-B8CA-43C8-B39E-6797066CBD7E@FreeBSD.org> In-Reply-To: <3373772881814803857@scdbackup.webframe.org> References: <D606FA1E-8E53-4D57-8A3C-2914B92385D6@FreeBSD.org> <3373772881814803857@scdbackup.webframe.org>
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> On Mar 22, 2018, at 1:48 PM, Thomas Schmitt <scdbackup@gmx.net> wrote: >=20 > Hi, >=20 > Benno Rice wrote: >> 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. >=20 > Waving friendly over the fence i feel entitled to give some neighbor's > review. Hello! Thanks for your response. [snip] >> https://people.freebsd.org/~benno/hybrid-bootonly.iso.xz >=20 > This does not look much like it addresses EFI. >=20 > $ xorriso -indev hybrid-bootonly.iso -report_el_torito plain = -report_system_area plain > ... > El Torito catalog : 19 1 > El Torito images : N Pltf B Emul Ld_seg Hdpt Ldsiz = LBA > El Torito boot img : 1 BIOS y none 0x0000 0x00 4 = 20 > El Torito boot img : 2 BIOS y none 0x0000 0x00 1600 = 24 > ... > MBR partition table: N Status Type Start Blocks > MBR partition : 1 0x80 0xa5 1 16 >=20 > UEFI 2.4, 12.3.2.1, says about El Torito: > "A Platform Id of 0xEF indicates an EFI System Partition." > But entry 2 of this catalog is in a section with Platform Id 0x00 (x86 = BIOS). >=20 > If byte 38977 (decimal) was 0xef rather than 0x00, then it would be = marked > as an El Torito boot image for EFI. I think I=E2=80=99ve addressed this in this revision: https://svnweb.freebsd.org/changeset/base/331463 = <https://svnweb.freebsd.org/changeset/base/331463>; And I=E2=80=99ve regenerated the image here: https://people.freebsd.org/~benno/hybrid-bootonly-20180323-00.iso.xz = <https://people.freebsd.org/~benno/hybrid-bootonly-20180323-00.iso.xz>; > Further: This section begins at byte address 38976 by a byte value = 0x90. > According to El Torito specs this means that another section follows. > Correct would be value 0x91, which announces the end of the catalog. > (El Torito 1.0, Figure 4, Offset 0) I=E2=80=99ll look into this too. > On HDD, EFI looks for specially marked partitions in GPT or MBR = partition > table. > In MBR partiton table it looks for a partition of type 0xEF. > (UEFI 2.4, 5.2.2) > In GPT it looks for Type GUID C12A7328-F81F-11D2-BA4B-00A0C93EC93B. > (UEFI 2.4, Table 19) >=20 > So to mark the EFI partition, hybrid-bootonly.iso should have a MBR > partition number 2 with type 0xEF, start at 512-byte block 24*2048/512 = =3D 96, > size 1600 blocks. > (Strangely El Torito addresses by 2048-byte blocks but counts by = 512-byte > blocks. Size limit is 65535 blocks. But counts 0 and 1 mean to EFI > "up to end of medium=E2=80=9D.) I=E2=80=99ll look in to this one too. >> I=E2=80=99ve tested this image under qemu=20 >=20 > OVMF/SDK-II/Tianocore is too tolerant with the EFI specs and with = silently > using BIOS boot equipment. Real iron EFIs insist much more in = compliance. So it appears. Thanks again for looking at this! Thanks, Benno.=
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