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>
index | next in thread | previous in thread | raw e-mail
> On Mar 22, 2018, at 1:48 PM, Thomas Schmitt <scdbackup@gmx.net> wrote: > > Hi, > > Benno Rice wrote: >> I’ve been working on the ability to create hybrid ISO/HDD boot images for >> x86, a la what Linux systems do with ISOHYBRID. > > 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 > > This does not look much like it addresses EFI. > > $ 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 > > 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). > > 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’ve addressed this in this revision: https://svnweb.freebsd.org/changeset/base/331463 <https://svnweb.freebsd.org/changeset/base/331463>; And I’ve 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’ll 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) > > 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 = 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”.) I’ll look in to this one too. >> I’ve tested this image under qemu > > 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.help
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?35FF5A67-B8CA-43C8-B39E-6797066CBD7E>