From b433f551c6cfd85fb40098b5e9253db2327a8cea Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Thu, 27 Jun 1991 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1991-06-27

---
 pc/l.s         | 96 +++++++++++++++++++++++++++++++++++++++-----------
 pc/mem.h       | 17 +++++++++
 pc/mmu.c       | 14 --------
 port/devscsi.c |  6 +++-
 port/portfns.h | 26 +++++++-------
 5 files changed, 111 insertions(+), 48 deletions(-)

diff --git a/pc/l.s b/pc/l.s
index 678eb77d277a9aa6508c0bb33783fe29c4ef8ea0..da3e830e53aabe92f286b094097005f5b7b11c03 100644
--- a/pc/l.s
+++ b/pc/l.s
@@ -1,41 +1,97 @@
 #include "mem.h"
 
+TEXT	start(SB),$0
+
+	JMP	start16
+
 /*
- *  pointer to initial gdt (must be in first 64K of program)
+ *  gdt to get us to 32-bit/segmented/unpaged mode
  */
-GLOBL	gdtptr(SB),$6
+TEXT	tgdt(SB),$0
+
+	/* null descriptor */
+	LONG	$0
+	LONG	$0
+
+	/* data segment descriptor for 4 gigabytes (PL 0) */
+	LONG	SEGG|SEGB|(0xF<<16)|SEGP|SEGPL(0)|SEGDATA|SEGW
+	LONG	0xFFFF
 
-	DATA	gdtptr+0(SB)/2, $(5*8)
-	DATA	gdtptr+2(SB)/4, $gdt(SB)
+	/* exec segment descriptor for 4 gigabytes (PL 0) */
+	LONG	SEGG|SEGD|(0xF<<16)|SEGP|SEGPL(p)|SEGEXEC|SEGR
+	LONG	0xFFFF
 
 /*
- *  pointer to idt (must be in first 64K of program)
+ *  pointer to initial gdt
  */
-GLOBL	idtptr(SB),$6
+TEXT	tgdtptr(SB),$0
 
-	DATA	idtptr+0(SB)/2, $(6*8)
-	DATA	idtptr+2(SB)/4, $idt(SB)
+	WORD	$(3*8)
+	LONG	$tgdt(SB)
 
 /*
- *  boot processor
+ *  come here in (16bit) real-address mode
  */
-TEXT	start(SB),$0
-
+start16:
 	CLI			/* disable interrupts */
 
-	/* point CPU at the interrupt/trap table */
-	LEAL	idtptr(SB),AX
-/*	MOVL	(AX),IDTR /**/
-
 	/* point data segment at low memory */
 	XORL	AX,AX
-/*	MOVW	AX,DS /**/
+	MOVW	AX,DS
+
+	/* point CPU at the interrupt descriptor table */
+	MOVL	tgdt(SB),IDTR
 
-	/* point CPU at the interrupt/trap table */
-	LEAL	gdtptr(SB),AX
-/*	MOVL	(AX),GDTR /**/
+	/* point CPU at the global descriptor table */
+	MOVL	gdtptr(SB),GDTR
 
-	CALL	main(SB)
+	/* switch to protected mode */
+	MOVL	CR0,AX
+	ORL	$1,AX
+	MOVL	AX,CR0
+
+	/* clear prefetch buffer */
+	JMP	flush
+
+/*
+ *  come here in USE16 protected mode
+ */
+flush:
+	/* map data and stack address to physical memory */
+	MOVW	$SELECTOR(1, SELGDT, 0),AX
+	MOVW	AX,DS
+	MOVW	AX,ES
+	MOVW	AX,SS
+
+	/* switch to 32 bit code */
+	JMPFAR	SELECTOR(2, SELGDT, 0):start32
+
+/*
+ *  come here in USE32 protected mode
+ */
+TEXT	start32(SB),$0
+
+	/* clear bss (should use REP) */
+	MOVL	$edata(SB),SI
+	MOVL	$edata+4(SB),DI
+	MOVL	$end(SB),CX
+	SUBL	DI,CX
+	SHRL	$2,CX
+	XORL	AX,AX
+	MOVL	AX,edata(SB)
+	CLD
+	REP
+	MOVSL	(SI),(DI)
+
+	/* set up stack */
+	MOVL	$mach0(SB),AX
+	MOVL	A0, m(SB)
+	MOVL	$0, 0(A0)
+	MOVL	A0, A7
+	ADDL	$(MACHSIZE-4), A7	/* start stack under machine struct */
+	MOVL	$0, u(SB)
+
+	CALL	main(SB),$0
 	/* never returns */
 
 /*
diff --git a/pc/mem.h b/pc/mem.h
index eac82bc12133d0fab503c327ce8c38449da6293e..2e6ed7dc1e06e3f2a100602fa144045f84450faa 100644
--- a/pc/mem.h
+++ b/pc/mem.h
@@ -78,3 +78,20 @@
 #define UDSEL	SELECTOR(UDSEG, SELGDT, 3)
 #define USSEL	SELECTOR(UDSEG, SELGDT, 3)
 
+/*
+ *  fields in segment descriptors
+ */
+#define SEGDATA	(0x10<<8)	/* data/stack segment */
+#define SEGEXEC	(0x18<<8)	/* executable segment */
+#define SEGCG	(0x0C<<8)	/* call gate */
+#define	SEGIG	(0x0E<<8)	/* interrupt gate */
+#define SEGTG	(0x0F<<8)	/* task gate */
+
+#define SEGP	(1<<15)		/* segment present */
+#define SEGPL(x) ((x)<<13)	/* priority level */
+#define SEGB	(1<<22)		/* granularity 1==4k (for expand-down) */
+#define SEGG	(1<<23)		/* granularity 1==4k (for other) */
+#define SEGE	(1<<10)		/* expand down */
+#define SEGW	(1<<9)		/* writable (for data/stack) */
+#define	SEGR	(1<<9)		/* readable (for code) */
+#define SEGD	(1<<22)		/* default 1==32bit (for code) */
diff --git a/pc/mmu.c b/pc/mmu.c
index 2663b0ea8dff821bacfe1ec592a50a69f47a7846..7f2fdcd12d078aa97e1ff9e278643255b1fe0f88 100644
--- a/pc/mmu.c
+++ b/pc/mmu.c
@@ -14,20 +14,6 @@ struct Segdesc
 	ulong	d0;
 	ulong	d1;
 };
-#define SEGDATA	(0x10<<8)	/* data/stack segment */
-#define SEGEXEC	(0x18<<8)	/* executable segment */
-#define SEGCG	(0x0C<<8)	/* call gate */
-#define	SEGIG	(0x0E<<8)	/* interrupt gate */
-#define SEGTG	(0x0F<<8)	/* task gate */
-
-#define SEGP	(1<<15)		/* segment present */
-#define SEGPL(x) ((x)<<13)	/* priority level */
-#define SEGB	(1<<22)		/* granularity 1==4k (for expand-down) */
-#define SEGG	(1<<23)		/* granularity 1==4k (for other) */
-#define SEGE	(1<<10)		/* expand down */
-#define SEGW	(1<<9)		/* writable (for data/stack) */
-#define	SEGR	(1<<9)		/* readable (for code) */
-#define SEGD	(1<<22)		/* default 1==32bit (for code) */
 
 /*
  *  gate initializers
diff --git a/port/devscsi.c b/port/devscsi.c
index 1499e86bb4c8833ab4a5dce894ef6edba0fd1c63..0314ec8cec16b9411f32b60927661c0eb564c03f 100644
--- a/port/devscsi.c
+++ b/port/devscsi.c
@@ -104,7 +104,7 @@ scsiwalk(Chan *c, char *name)
 void
 scsistat(Chan *c, char *db)
 {
-	devstat(c, db, 0, 0, scsigen);
+	devstat(c, db, 0, 0, scsigeno);
 }
 
 Chan *
@@ -579,5 +579,9 @@ scsictrlintr(void)
 		default:
 			panic("scsi status 0x%2.2ux", status);
 		}
+		kprint("resetting...");
+		PUT(Own_id, ownid);
+		PUT(Cmd, Reset);
+		break;
 	}
 }
diff --git a/port/portfns.h b/port/portfns.h
index 45a6f0261246ee8ea82c12965d01739a14e3b9c7..ac5c040e2788e38ffb082421cf93bb914d2408c3 100644
--- a/port/portfns.h
+++ b/port/portfns.h
@@ -1,8 +1,8 @@
 #define	SET(x)	x = 0
 #define	USED(x)	if(x)
 
-void	alarminit(void);
 Alarm*	alarm(int, void (*)(Alarm*), void*);
+void	alarminit(void);
 Block*	allocb(ulong);
 int	anyready(void);
 void	append(List**, List*);
@@ -12,8 +12,8 @@ void	buzz(int, int);
 void	cancel(Alarm*);
 int	cangetc(void*);
 int	canlock(Lock*);
-int	canqlock(QLock*);
 int	canputc(void*);
+int	canqlock(QLock*);
 void	chandevinit(void);
 void	chandevreset(void);
 void	chaninit(void);
@@ -30,8 +30,8 @@ int	consactive(void);
 Env*	copyenv(Env*, int);
 int	decref(Ref*);
 void	delay(int);
-void	delete0(List**, List*);
 void	delete(List**, List*, List*);
+void	delete0(List**, List*);
 Chan*	devattach(int, char*);
 Chan*	devclone(Chan*, Chan*);
 void	devdir(Chan*, Qid, char*, long, long, Dir*);
@@ -45,8 +45,8 @@ void*	dmaalloc(ulong);
 void	dumpqueues(void);
 void	dumpregs(Ureg*);
 void	dumpstack(void);
-void	envpgclose(Env *);
 void	envcpy(Pgrp*, Pgrp*);
+void	envpgclose(Env *);
 int	eqchan(Chan*, Chan*, long);
 int	eqqid(Qid, Qid);
 void	error(int);
@@ -82,8 +82,8 @@ void	insert(List**, List*, List*);
 void	invalidateu(void);
 void	isdir(Chan*);
 void	kbdclock(void);
-void	kbdrepeat(int);
 int	kbdputc(IOQ*, int);
+void	kbdrepeat(int);
 int	kprint(char*, ...);
 void	kproc(char*, void(*)(void*), void*);
 void	lights(int);
@@ -95,8 +95,8 @@ Orig*	lookorig(ulong, ulong, int, Chan*);
 void	machinit(void);
 void	mapstack(Proc*);
 void	mklockseg(Seg*);
-void	mntdump(void);
 void	mmurelease(Proc*);
+void	mntdump(void);
 int	mount(Chan*, Chan*, int);
 int	mouseputc(IOQ*, int);
 Chan*	namec(char*, int, int, ulong);
@@ -126,10 +126,6 @@ Pgrp*	pgrptab(int);
 int	postnote(Proc*, int, char*, int);
 int	pprint(char*, ...);
 void	printinit(void);
-int	putc(IOQ*, int);
-void	putstr(char*);
-void	putstrn(char*, long);
-void	puts(IOQ*, void*, int);
 ulong 	procalarm(ulong);
 void	procdump(void);
 void	procinit0(void);
@@ -138,8 +134,12 @@ Block*	pullup(Block *, int);
 Queue*	pushq(Stream*, Qinfo*);
 int	putb(Blist*, Block*);
 void	putbq(Blist*, Block*);
+int	putc(IOQ*, int);
 void	putmmu(ulong, ulong);
 int	putq(Queue*, Block*);
+void	puts(IOQ*, void*, int);
+void	putstr(char*);
+void	putstrn(char*, long);
 ulong	pwait(Waitmsg*);
 void	qlock(QLock*);
 void	qunlock(QLock*);
@@ -153,8 +153,8 @@ void	sccintr(void);
 void	sccputs(IOQ*, char*, int);
 void	sccsetup(void*);
 void	sccspecial(int, IOQ*, IOQ*, int);
-void	schedinit(void);
 void	sched(void);
+void	schedinit(void);
 long	seconds(void);
 Seg*	seg(Proc*, ulong);
 int	segaddr(Seg*, ulong, ulong);
@@ -164,13 +164,13 @@ void	sleep(Rendez*, int(*)(void*), void*);
 int	splhi(void);
 int	spllo(void);
 void	splx(int);
-int	streamclose1(Stream*);
 int	streamclose(Chan*);
+int	streamclose1(Stream*);
 int	streamenter(Stream*);
 int	streamexit(Stream*, int);
 Devgen	streamgen;
-void	streaminit0(void);
 void	streaminit(void);
+void	streaminit0(void);
 Stream*	streamnew(ushort, ushort, ushort, Qinfo*, int);
 void	streamopen(Chan*, Qinfo*);
 int	streamparse(char*, Block*);