Date: Mon, 12 Jan 2004 15:30:20 -0500 From: John Baldwin <jhb@FreeBSD.org> To: Martin Nilsson <martin@gneto.com>, Marcin Dalecki <mdcki@gmx.net> Cc: freebsd-hackers@freebsd.org Subject: Re: Assembler coding help needed. [solved, patch enclosed] Message-ID: <200401121530.20732.jhb@FreeBSD.org> In-Reply-To: <4001C283.5080106@gneto.com> References: <4001552B.5060108@gneto.com> <4001A184.5060301@gmx.net> <4001C283.5080106@gneto.com>
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On Sunday 11 January 2004 04:39 pm, Martin Nilsson wrote: > Marcin Dalecki wrote: > > Martin Nilsson wrote: > >> I'm trying to find out why I can't boot 5.2 from USB CDROM on > >> Supermicro motherboards. (I have an old Gateway P3 that can!). > >> > >> I've found out that that only 0x20 of 0x4c sectors of the loader are > >> read in and it therfor traps when executed. (read is only called once). > >> > >> load_notrunc: sub %dh,%cl # Update count > >> push %eax # Save > >> call read # Read it in > > > > The fun will be ^^^^ here. The rest is self contained and > > doesn't depend on CPU variant or periphery. > > I found the problem! > The bios trashes %cx when reading from USB CD but not when reading from > ATAPI CD. > > The attached patch fixes this and two other small nits in > sys/boot/i386/cdboot/cdboot.s Thanks for the nit fixes. > Can somebody (jhb) commit this? > > This probably affects all Phoenix-Award bios equipped boxes. My old > Gateway with AMI BIOS works as it should. I will commit something similar. I will save %cx around the BIOS call itself in the read function. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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