[x86 setup] APM: BX should be zero when disconnecting

For APM calls, BX contains the device index, which is zero for the system BIOS. Disconnect requres BX = 0. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
git-mirror · Jul 25, 2007 · 1a13286 · 1a13286
1 parent 1514ab0
commit 1a13286
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/arch/i386/boot/apm.c b/arch/i386/boot/apm.c
@@ -45,9 +45,10 @@ int query_apm_bios(void)
 
 	/* Disconnect first, just in case */
 	ax = 0x5304;
+	bx = 0;
 	asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp"
-		     : "+a" (ax)
-		     : : "ebx", "ecx", "edx", "esi", "edi");
+		     : "+a" (ax), "+b" (bx)
+		     : : "ecx", "edx", "esi", "edi");
 
 	/* Paranoia */
 	ebx = esi = 0;