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remove realmode and e820 code from kernel

--- a/sys/man/8/plan9.ini

+++ b/sys/man/8/plan9.ini

@@ -642,13 +642,6 @@

 and

 .I end

 addresses of the usable memory areas.

-.SS \fL*norealmode=\fP

-The PC kernel switches the processor to 16-bit real mode

-to run BIOS interrupts, for example to find the memory map or to enable VESA.

-This variable disables such switches.

-.SS \fL*noe820scan=\fP

-When available, the PC kernel uses the BIOS E820 memory map

-to size memory.  This variable disables the scan.

 .SS \fL*maxmem=\fIvalue\fP

 This defines the maximum physical address that the system will scan when sizing memory.

 By default the PC operating system will scan up to 3.75 gigabytes

--- a/sys/src/9/pc/devarch.c

+++ b/sys/src/9/pc/devarch.c

@@ -989,6 +989,39 @@

 	return n;

 }

+static long

+rmemrw(int isr, void *a, long n, vlong off)

+{

+	if(off < 0 || n < 0)

+		error("bad offset/count");

+	if(isr){

+		if(off >= MB)

+			return 0;

+		if(off+n >= MB)

+			n = MB - off;

+		memmove(a, KADDR((ulong)off), n);

+	}else{

+		/* allow vga framebuf's access */

+		if(off >= MB || off+n > MB ||

+		    (off < 0xA0000 || off+n > 0xB0000+0x10000))

+			error("bad offset/count in write");

+		memmove(KADDR((ulong)off), a, n);

+	}

+	return n;

+}

+

+static long

+rmemread(Chan*, void *a, long n, vlong off)

+{

+	return rmemrw(1, a, n, off);

+}

+

+static long

+rmemwrite(Chan*, void *a, long n, vlong off)

+{

+	return rmemrw(0, a, n, off);

+}

+

 void

 archinit(void)

 {

@@ -1037,6 +1070,7 @@

 	addarchfile("cputype", 0444, cputyperead, nil);

 	addarchfile("archctl", 0664, archctlread, archctlwrite);

+	addarchfile("realmodemem", 0660, rmemread, rmemwrite);

 }

 /*

--- a/sys/src/9/pc/l.s

+++ b/sys/src/9/pc/l.s

@@ -310,178 +310,6 @@

 	RET

 /*

- * Assumed to be in protected mode at time of call.

- * Switch to real mode, execute an interrupt, and

- * then switch back to protected mode.  

- *

- * Assumes:

- *

- *	- no device interrupts are going to come in

- *	- 0-16MB is identity mapped in page tables

- *	- realmode() has copied us down from 0x100000 to 0x8000

- *	- can use code segment 0x0800 in real mode

- *		to get at l.s code

- *	- l.s code is less than 1 page

- */

-#define RELOC	(RMCODE-KTZERO)

-

-TEXT realmodeidtptr(SB), $0

-	WORD	$(4*256-1)

-	LONG	$0

-

-TEXT realmode0(SB), $0

-	CALL	saveregs(SB)

-

-	/* switch to low code address */

-	LEAL	physcode-KZERO(SB), AX

-	JMP *AX

-

-TEXT physcode(SB), $0

-

-	/* switch to low stack */

-	MOVL	SP, AX

-	MOVL	$0x7C00, SP

-	PUSHL	AX

-

-	/* change gdt to physical pointer */

-	MOVL	m0rgdtptr-KZERO(SB), GDTR

-

-	/* load IDT with real-mode version*/

-	MOVL	realmodeidtptr-KZERO(SB), IDTR

-

-	/* edit INT $0x00 instruction below */

-	MOVL	$(RMUADDR-KZERO+48), AX	/* &rmu.trap */

-	MOVL	(AX), AX

-	MOVB	AX, realmodeintrinst+(-KZERO+1+RELOC)(SB)

-

-	/* disable paging */

-	MOVL	CR0, AX

-	ANDL	$0x7FFFFFFF, AX

-	MOVL	AX, CR0

-	/* JMP .+2 to clear prefetch queue*/

-	BYTE $0xEB; BYTE $0x00

-

-	/* jump to 16-bit code segment */

-/*	JMPFAR	SELECTOR(KESEG16, SELGDT, 0):$again16bit(SB) /**/

-	 BYTE	$0xEA

-	 LONG	$again16bit-KZERO(SB)

-	 WORD	$SELECTOR(KESEG16, SELGDT, 0)

-

-TEXT again16bit(SB), $0

-	/*

-	 * Now in 16-bit compatibility mode.

-	 * These are 32-bit instructions being interpreted

-	 * as 16-bit instructions.  I'm being lazy and

-	 * not using the macros because I know when

-	 * the 16- and 32-bit instructions look the same

-	 * or close enough.

-	 */

-

-	/* disable protected mode and jump to real mode cs */

-	OPSIZE; MOVL CR0, AX

-	OPSIZE; XORL BX, BX

-	OPSIZE; INCL BX

-	OPSIZE; XORL BX, AX

-	OPSIZE; MOVL AX, CR0

-

-	/* JMPFAR 0x0800:now16real */

-	 BYTE $0xEA

-	 WORD	$now16real-KZERO(SB)

-	 WORD	$0x0800

-

-TEXT now16real(SB), $0

-	/* copy the registers for the bios call */

-	LWI(0x0000, rAX)

-	MOVW	AX,SS

-	LWI(RMUADDR, rBP)

-	

-	/* offsets are in Ureg */

-	LXW(44, xBP, rAX)

-	MOVW	AX, DS

-	LXW(40, xBP, rAX)

-	MOVW	AX, ES

-

-	OPSIZE; LXW(0, xBP, rDI)

-	OPSIZE; LXW(4, xBP, rSI)

-	OPSIZE; LXW(16, xBP, rBX)

-	OPSIZE; LXW(20, xBP, rDX)

-	OPSIZE; LXW(24, xBP, rCX)

-	OPSIZE; LXW(28, xBP, rAX)

-

-	CLC

-

-TEXT realmodeintrinst(SB), $0

-	INT $0x00

-

-	/* save the registers after the call */

-

-	LWI(0x7bfc, rSP)

-	OPSIZE; PUSHFL

-	OPSIZE; PUSHL AX

-

-	LWI(0, rAX)

-	MOVW	AX,SS

-	LWI(RMUADDR, rBP)

-	

-	OPSIZE; SXW(rDI, 0, xBP)

-	OPSIZE; SXW(rSI, 4, xBP)

-	OPSIZE; SXW(rBX, 16, xBP)

-	OPSIZE; SXW(rDX, 20, xBP)

-	OPSIZE; SXW(rCX, 24, xBP)

-	OPSIZE; POPL AX

-	OPSIZE; SXW(rAX, 28, xBP)

-

-	MOVW	DS, AX

-	OPSIZE; SXW(rAX, 44, xBP)

-	MOVW	ES, AX

-	OPSIZE; SXW(rAX, 40, xBP)

-

-	OPSIZE; POPL AX

-	OPSIZE; SXW(rAX, 64, xBP)	/* flags */

-

-	/* re-enter protected mode and jump to 32-bit code */

-	OPSIZE; MOVL $1, AX

-	OPSIZE; MOVL AX, CR0

-	

-/*	JMPFAR	SELECTOR(KESEG, SELGDT, 0):$again32bit(SB) /**/

-	 OPSIZE

-	 BYTE $0xEA

-	 LONG	$again32bit-KZERO(SB)

-	 WORD	$SELECTOR(KESEG, SELGDT, 0)

-

-TEXT again32bit(SB), $0

-	MOVW	$SELECTOR(KDSEG, SELGDT, 0),AX

-	MOVW	AX,DS

-	MOVW	AX,SS

-	MOVW	AX,ES

-	MOVW	AX,FS

-	MOVW	AX,GS

-

-	/* enable paging and jump to kzero-address code */

-	MOVL	CR0, AX

-	ORL	$0x80010000, AX	/* PG|WP */

-	MOVL	AX, CR0

-	LEAL	again32kzero(SB), AX

-	JMP*	AX

-

-TEXT again32kzero(SB), $0

-	/* breathe a sigh of relief - back in 32-bit protected mode */

-

-	/* switch to old stack */	

-	PUSHL	AX	/* match popl below for 8l */

-	MOVL	$0x7BFC, SP

-	POPL	SP

-

-	/* restore idt */

-	MOVL	m0idtptr(SB),IDTR

-

-	/* restore gdt */

-	MOVL	m0gdtptr(SB), GDTR

-

-	CALL	restoreregs(SB)

-	RET

-

-/*

  * BIOS32.

  */

 TEXT bios32call(SB), $0

--- a/sys/src/9/pc/mem.h

+++ b/sys/src/9/pc/mem.h

@@ -60,8 +60,6 @@

 #define	CONFADDR	(KZERO+0x1200)		/* info passed from boot loader */

 #define	TMPADDR		(KZERO+0x2000)		/* used for temporary mappings */

 #define	APBOOTSTRAP	(KZERO+0x3000)		/* AP bootstrap code */

-#define	RMUADDR		(KZERO+0x7C00)		/* real mode Ureg */

-#define	RMCODE		(KZERO+0x8000)		/* copy of first page of KTEXT */

 #define	RMBUF		(KZERO+0x9000)		/* buffer for user space - known to vga */

 #define	IDTADDR		(KZERO+0x10800)		/* idt */

 #define	REBOOTADDR	(0x11000)		/* reboot code - physical address */

--- a/sys/src/9/pc/memory.c

+++ b/sys/src/9/pc/memory.c

@@ -526,20 +526,10 @@

 {

 	uvlong base;

 	uvlong len;

-	ulong type;

 };

 static Emap emap[16];

 int nemap;

-static char *etypes[] =

-{

-	"type=0",

-	"memory",

-	"reserved",

-	"acpi reclaim",

-	"acpi nvs",

-};

-

 static int

 emapcmp(const void *va, const void *vb)

 {

@@ -551,11 +541,7 @@

 		return -1;

 	if(a->base > b->base)

 		return 1;

-	if(a->len < b->len)

-		return -1;

-	if(a->len > b->len)

-		return 1;

-	return a->type - b->type;

+	return a->len - b->len;

 }

 static void

@@ -668,66 +654,29 @@

 static int

 e820scan(void)

 {

-	int i;

-	Ureg u;

-	ulong cont, base, len;

+	ulong base, len;

 	uvlong last;

 	Emap *e;

 	char *s;

+	int i;

-	if((s = getconf("e820")) != nil){

-		for(nemap = 0; nemap < nelem(emap); nemap++){

-			if(*s == 0)

-				break;

-			e = emap + nemap;

-			e->base = strtoull(s, &s, 16);

-			if(*s != ' ')

-				break;

-			e->len = strtoull(s, &s, 16) - e->base;

-			if(*s != ' ' && *s != 0 || e->len >= 1ull<<32 || e->len == 0)

-				break;

-			e->type = Ememory;

-		}

-	}else{

-		if(getconf("*norealmode") || getconf("*noe820scan"))

-			return -1;

-		cont = 0;

-		for(i=0; i<nelem(emap); i++){

-			memset(&u, 0, sizeof u);

-			u.ax = 0xE820;

-			u.bx = cont;

-			u.cx = 20;

-			u.dx = SMAP;

-			u.es = (PADDR(RMBUF)>>4)&0xF000;

-			u.di = PADDR(RMBUF)&0xFFFF;

-			u.trap = 0x15;

-			realmode(&u);

-			cont = u.bx;

-			if((u.flags&Carry) || u.ax != SMAP || u.cx != 20)

-				break;

-			e = &emap[nemap++];

-			*e = *(Emap*)RMBUF;

-			if(u.bx == 0)

-				break;

-		}

+	/* passed by bootloader */

+	if((s = getconf("e820")) == nil)

+		return -1;

+	for(nemap = 0; nemap < nelem(emap); nemap++){

+		if(*s == 0)

+			break;

+		e = emap + nemap;

+		e->base = strtoull(s, &s, 16);

+		if(*s != ' ')

+			break;

+		e->len = strtoull(s, &s, 16) - e->base;

+		if(*s != ' ' && *s != 0 || e->len >= 1ull<<32 || e->len == 0)

+			break;

 	}

-

 	if(nemap == 0)

 		return -1;

-	

 	qsort(emap, nemap, sizeof emap[0], emapcmp);

-

-	if(s == nil && getconf("*noe820print") == nil){

-		for(i=0; i<nemap; i++){

-			e = &emap[i];

-			print("E820: %.8llux %.8llux ", e->base, e->base+e->len);

-			if(e->type < nelem(etypes))

-				print("%s\n", etypes[e->type]);

-			else

-				print("type=%lud\n", e->type);

-		}

-	}

-

 	last = 0;

 	for(i=0; i<nemap; i++){	

 		e = &emap[i];

@@ -747,10 +696,7 @@

 		if(last < e->base)

 			map(last, e->base-last, MemUPA);

 		last = base+len;

-		if(e->type == Ememory)

-			map(base, len, MemRAM);

-		else

-			map(base, len, MemReserved);

+		map(base, len, MemRAM);

 	}

 	if(last < (1LL<<32))

 		map(last, (u32int)-last, MemUPA);

--- a/sys/src/9/pc/pccpuf

+++ b/sys/src/9/pc/pccpuf

@@ -38,7 +38,6 @@

 link

 	segdesc

-	realmode

 	devpccard

 	devi82365

 	apm		apmjump

--- a/sys/src/9/pc/pcf

+++ b/sys/src/9/pc/pcf

@@ -39,7 +39,6 @@

 link

 	segdesc

-	realmode

 	devpccard

 	devi82365

 	apm		apmjump

--- a/sys/src/9/pc/realmode.c

+++ /dev/null

@@ -1,140 +1,0 @@

-#include	"u.h"

-#include	"tos.h"

-#include	"../port/lib.h"

-#include	"mem.h"

-#include	"dat.h"

-#include	"fns.h"

-#include	"io.h"

-#include	"ureg.h"

-#include	"../port/error.h"

-

-/*

- * Back the processor into real mode to run a BIOS call,

- * then return.  This must be used carefully, since it 

- * completely disables hardware interrupts (e.g., the i8259)

- * while running.  It is *not* using VM86 mode. 

- * Maybe that's really the right answer, but real mode

- * is fine for now.  We don't expect to use this very much --

- * just for VGA and APM.

- */

-#define realmoderegs (*(Ureg*)RMUADDR)

-

-#define LORMBUF (RMBUF-KZERO)

-

-static Ureg rmu;

-static Lock rmlock;

-

-void

-realmode(Ureg *ureg)

-{

-	int s;

-	ulong cr3;

-	extern void realmode0(void);	/* in l.s */

-

-	if(getconf("*norealmode"))

-		return;

-

-	lock(&rmlock);

-	realmoderegs = *ureg;

-

-	/* copy l.s so that it can be run from 16-bit mode */

-	memmove((void*)RMCODE, (void*)KTZERO, 0x1000);

-

-	s = splhi();

-	m->pdb[PDX(0)] = m->pdb[PDX(KZERO)];	/* identity map low */

-	cr3 = getcr3();

-	putcr3(PADDR(m->pdb));

-	if (arch)

-		arch->introff();

-	else

-		i8259off();

-	realmode0();

-	if(m->tss){

-		/*

-		 * Called from memory.c before initialization of mmu.

-		 * Don't turn interrupts on before the kernel is ready!

-		 */

-		if (arch)

-			arch->intron();

-		else

-			i8259on();

-	}

-	m->pdb[PDX(0)] = 0;	/* remove low mapping */

-	putcr3(cr3);

-	splx(s);

-	*ureg = realmoderegs;

-	unlock(&rmlock);

-}

-

-static long

-rtrapread(Chan*, void *a, long n, vlong off)

-{

-	if(off < 0)

-		error("badarg");

-	if(n+off > sizeof rmu)

-		n = sizeof rmu - off;

-	if(n <= 0)

-		return 0;

-	memmove(a, (char*)&rmu+off, n);

-	return n;

-}

-

-static long

-rtrapwrite(Chan*, void *a, long n, vlong off)

-{

-	if(off || n != sizeof rmu)

-		error("write a Ureg");

-	memmove(&rmu, a, sizeof rmu);

-	/*

-	 * Sanity check

-	 */

-	if(rmu.trap == 0x10){	/* VBE */

-		rmu.es = (LORMBUF>>4)&0xF000;

-		rmu.di = LORMBUF&0xFFFF;

-	}else

-		error("invalid trap arguments");

-	realmode(&rmu);

-	return n;

-}

-

-static long

-rmemrw(int isr, void *a, long n, vlong off)

-{

-	if(off < 0 || n < 0)

-		error("bad offset/count");

-	if(isr){

-		if(off >= MB)

-			return 0;

-		if(off+n >= MB)

-			n = MB - off;

-		memmove(a, KADDR((ulong)off), n);

-	}else{

-		/* realmode buf page ok, allow vga framebuf's access */

-		if(off >= MB || off+n > MB ||

-		    (off < LORMBUF || off+n > LORMBUF+BY2PG) &&

-		    (off < 0xA0000 || off+n > 0xB0000+0x10000))

-			error("bad offset/count in write");

-		memmove(KADDR((ulong)off), a, n);

-	}

-	return n;

-}

-

-static long

-rmemread(Chan*, void *a, long n, vlong off)

-{

-	return rmemrw(1, a, n, off);

-}

-

-static long

-rmemwrite(Chan*, void *a, long n, vlong off)

-{

-	return rmemrw(0, a, n, off);

-}

-

-void

-realmodelink(void)

-{

-	addarchfile("realmode", 0660, rtrapread, rtrapwrite);

-	addarchfile("realmodemem", 0660, rmemread, rmemwrite);

-}

-

-- 

⑨