Be much more carefull about what we leave in unused registers when we call

the APM-bios.
This stabilizes a couple of APM bioses quite a bit.
They all make the mistake of going into 16-bit mode, without clearing the
top half of the 32bit registers.
Later they do a
|	movw %si,$0x7331
|	movw %ax,0x6(%si)
or something along those lines and crash and burn, because their segment
is already relocated, so adding 0xf0171ce9 to the base of it is bad news.

At least SystemSoft is guilty of this bummer.

1 files changed, 12 insertions, 2 deletions

diff --git a/sys/i386/apm/apm.c b/sys/i386/apm/apm.c
index d419da4..99c3582 100644
--- a/sys/i386/apm/apm.c
+++ b/sys/i386/apm/apm.c
@@ -13,7 +13,7 @@
  *
  * Sep, 1994	Implemented on FreeBSD 1.1.5.1R (Toshiba AVS001WD)
  *
- *	$Id: apm.c,v 1.6 1994/11/07 04:23:58 phk Exp $
+ *	$Id: apm.c,v 1.7 1994/11/15 14:09:18 bde Exp $
  */
 
 #include "apm.h"
@@ -92,11 +92,18 @@ apm_int(u_long *eax,u_long *ebx,u_long *ecx)
 	u_long cf;
 	__asm ("pushl	%%ebp
 		pushl	%%edx
+		pushl	%%esi
+		pushl	%%edi
 		xorl	%3,%3
+		movl	%%edi,%3
+		movl	%%esi,%3
 		lcall	_apm_addr
 		jnc	1f
 		incl	%3
-	1:	popl	%%edx
+	1:	
+		popl	%%edi
+		popl	%%esi
+		popl	%%edx
 		popl	%%ebp"
 		: "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=D" (cf)
 		: "0" (*eax),  "1" (*ebx),  "2" (*ecx)
@@ -175,6 +182,8 @@ apm_getevent(void)
 
 	eax = (APM_BIOS<<8) | APM_GETPMEVENT;
 	
+	ebx = 0;
+	ecx = 0;
 	if (apm_int(&eax,&ebx,&ecx))
 		return PMEV_NOEVENT;
 
@@ -243,6 +252,7 @@ apm_get_info(apm_info_t aip)
 
 	eax = (APM_BIOS<<8)|APM_GETPWSTATUS;
 	ebx = PMDV_ALLDEV;
+	ecx = 0;
 
 	if (apm_int(&eax,&ebx,&ecx))
 		return 1;