i386/52975: CPUTYPE=k7 results in non-functional /boot/loader

[Garrett Wollman]

>Number:         52975
>Category:       i386
>Synopsis:       CPUTYPE=k7 results in non-functional /boot/loader
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jun 05 20:50:11 PDT 2003
>Closed-Date:
>Last-Modified:
>Originator:     Garrett Wollman
>Release:        FreeBSD 5.1-BETA i386
>Organization:
MIT Laboratory for Computer Science
>Environment:
System: FreeBSD hergotha.lcs.mit.edu 5.1-BETA FreeBSD 5.1-BETA #16: Sun Jun 1 22:15:28 EDT 2003 root at hergotha.lcs.mit.edu:/usr/src/sys/i386/compile/HERGOTHA i386

>Description:

	CPUTYPE=k7 results in a boot loader that doesn't.  It appears to 
	be entirely unable to read the hard disk (although accesses to the
	floppy seem to work fine)

>How-To-Repeat:

	make world with CPUTYPE?=k7 in /etc/make.conf
	Reboot
	Find out that the boot loader is unable to read the hard disk.

>Fix:

	This is probably a compiler bug.  Workaround is:

	Add NO_CPU_CFLAGS=yo to /sys/boot/Makefile.inc and
	/sys/boot/i386/Makefile.inc

	This generates a working boot loader.

	I suspect that the compiler may be generating code to use
	vector instructions somewhere, but these instructions do not
	work in the boot loader's environment.

>Release-Note:
>Audit-Trail:
>Unformatted: