Date: Wed, 01 Feb 2006 14:43:18 +0100 From: Martin Nilsson <martin@gneto.com> To: babkin@users.sf.net Cc: src-committers@freebsd.org, cvs-all@freebsd.org, cvs-src@freebsd.org, Scott Long <scottl@pooker.samsco.org> Subject: Re: cvs commit: src/release Makefile Message-ID: <43E0BAF6.4080501@gneto.com> In-Reply-To: <3362285.1138799355022.JavaMail.root@vms170.mailsrvcs.net> References: <3362285.1138799355022.JavaMail.root@vms170.mailsrvcs.net>
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Sergey Babkin skrev: >> From: Peter Jeremy <peterjeremy@optushome.com.au> > >> Some time ago, I was surprised to find that my son's oldish (mid 2003) >> system was happy to try and boot off a USB memory stick. > > The BIOSes have been able to do this feat for a while now. There are two caveats though: > > 1. It's slow, since BIOSes tend to use USB 1.x speeds, > and even that not in a really fast way. So the big > images are best to be avoided. Though probably it's > still faster than floppies. > > 2. Accessing the root filesystem - the USB drivers > have to be either statically compiled into the > kernel or be loaded by the boot loader through BIOS > (maybe through an analog of initrd ram disk - I'm > not sure what advances have been done to the FreeBSD > boot loader nowadays). There is another major caveat for some BIOSes: 3. The BTX loader is a 32-bit program that calls the BIOS functions via v86 calls, these calls fails on some BIOSes when a disk/cd is attached with USB resulting in the infamous BTX halted error. I've been told that this is due to the fact that the BIOS tries to enter 32-bit mode again not realizing that the CPU already is in this mode. I recently found out that there is something called BIOS32, a 32-bit interface to the BIOS functions. More info here: http://www.mega-tokyo.com/osfaq2/index.php/I%20heard%20you%20can%20do%20PCI%20calls%20with%20the%20BIOS%20in%20Protected%20Mode%3F I haven't had time to see if calling the function that blows up when booting from USB-CD (check which drives are available) thru BIOS32 is going to work or not. I have lots of boards that have this problem (Supermicro P8SCi for one), if someone wants to have any changes tested. I thought using a USB thumb drive instead of a CD-RW would be easier but I haven't had time to do anything with yet. /Martin
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