From 015cd976c6ff9a00fded2edbc617daf85b7b3ca1 Mon Sep 17 00:00:00 2001
From: Joshua Wise <joshua@rebirth.joshuawise.com>
Date: Fri, 5 Sep 2008 17:50:16 -0400
Subject: [PATCH] Don't clear BSS if we don't need to.

---
 aseg/Makefile  |  2 +-
 aseg/aseg.asm  | 30 +++++++++++++++++++-----------
 aseg/counter.c |  3 ++-
 3 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/aseg/Makefile b/aseg/Makefile
index 5bef71f..20e5ae9 100644
--- a/aseg/Makefile
+++ b/aseg/Makefile
@@ -6,5 +6,5 @@ aseg.bin: aseg.asm
 aseg.o: aseg.bin
 	objcopy -I binary -B i386 -O elf32-i386 aseg.bin aseg.o
 
-aseg.elf: aseg.bin aseg.lds counter.o
+aseg.elf: aseg.o aseg.lds counter.o
 	ld -o aseg.elf -T aseg.lds counter.o
diff --git a/aseg/aseg.asm b/aseg/aseg.asm
index ee83272..244cafc 100644
--- a/aseg/aseg.asm
+++ b/aseg/aseg.asm
@@ -74,29 +74,34 @@ continue:
 	mov al, [esp-6]
 	out dx, al
 
-	mov al, 0
-	mov edi, [dataptr+4]		; clear BSS
-	mov ecx, [dataptr+8]
-	rep stosb
-
 	mov dx, 0xCFC			; restore smramc
 	mov al, [esp-5]
 	out dx, al
-	
-	mov eax, [dataptr+12]
-	call eax
 
-	mov dx, 0xCF8			; restore the old config value
+	mov dx, 0xCF8			; restore the old PCI config value
 	mov eax, [esp-4]
 	out dx, eax
 
+	mov al, [needclear]
+	cmp al, 0
+	jz noclear
+	mov al, 0			; clear BSS
+	mov edi, [dataptr+4]
+	mov ecx, [dataptr+8]
+	rep stosb
+	mov [needclear], al
+	
+noclear:
+	mov eax, [dataptr+12]		; jump into C
+	call eax
+
 	mov al, 0x40			; ack the periodic IRQ
 	mov dx, 0x834
 	out dx, al
 	
-	mov dx, 0x830
+	mov dx, 0x830			; now ack the SMI itself
 	in al, dx
-	or al, 0x02			; now ack the SMI itself
+	or al, 0x02
 	and al, 0xBF
 	out dx, al
 	or al, 0x40
@@ -104,6 +109,9 @@ continue:
 
 	rsm				; and leave SMM
 
+needclear:
+	db 0x01
+
 	align 0x4
 gdtr:
 	db 0x27, 0x00
diff --git a/aseg/counter.c b/aseg/counter.c
index 891c075..edad021 100644
--- a/aseg/counter.c
+++ b/aseg/counter.c
@@ -3,7 +3,8 @@ char counter = 0;
 #define outb(port, val) \
 ({ asm volatile("outb %0, %%dx" : : "a" ((unsigned char)(val)) , "d" ((unsigned short)(port))); })
 
-void __start (void) {
+void __start (void)
+{
 	counter++;
 	outb (0x80, counter);
 }
-- 
2.39.2