Date: Thu, 22 Mar 2012 19:46:37 +0100 From: "Thomas Schmitt" <scdbackup@gmx.net> To: freebsd-hackers@freebsd.org Subject: Re: iso2flash img Message-ID: <10033788658207@192.168.2.69> In-Reply-To: <20120322173717.GA54005@onelab2.iet.unipi.it> References: <20120322173717.GA54005@onelab2.iet.unipi.it>
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Hi, > > The trick is called "isohybrid". Luigi Rizzo <rizzo@iet.unipi.it> wrote: > interesting. It does work for me indeed. So why not for Da Rock ? > And it might be a nice trick for our images too, so we don't > have to build a memstick and an ISO image... I would be happy to help with that. I am the developer of program xorriso which in the role of mkisofs has composed that Ubuntu image. My knowlege is only about pointing BIOS to the boot loader start programs, not about those boot systems themselves. A while ago i exercised the most simple case of http://wiki.freebsd.org/AvgLiveCD with the mkisofs emulation of xorriso. It booted. An MBR can be inserted easily by mkisofs option -G. isohybrid demands to patch that MBR with the LBA of the boot image and to set up the DOS partition table. GRUB2 demands only to set up the partition table. (Special xorrisofs options get employed.) What would a FreeBSD bootloader MBR need to know about the data in the ISO image to start up and handle it like a read-only hard disk ? Do programs of the first boot stages need to know their own LBA in the image resp. partition ? The El Torito and MBR equipment of GRUB2 can provide the same functionality as ISOLINUX with isohybrid. GRUB2 script grub-mkrescue demonstrates this. I understand Debian GNU/kFreeBSD boots via El Torito and GRUB2. But it makes no use of the opportunity to have an MBR too. I boot my own FreeBSD 8-STABLE from hard disk via MBR, GRUB2 and a chainloaded FreeBSD boot loader. Have a nice day :) Thomas
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