/* * boot driver for BIOS LBA devices * heavily dependent upon correct BIOS implementation */#include <u.h>#include "lib.h"#include "mem.h"#include "dat.h"#include "fns.h"#include "io.h"#include "ureg.h"#include "fs.h" typedef uvlong Devbytes, Devsects; typedef struct Biosdrive Biosdrive;	/* 1 drive -> ndevs */typedef struct Biosdev Biosdev; enum {	Debug = 0,	Pause = 0,			/* delay to read debugging */ 	Maxdevs		= 8,	CF		= 1,		/* carry flag: indicates an error */	Flopid		= 0,		/* first floppy */	Baseid		= 0x80,		/* first disk */ 	/* cx bits of Biosckext results */	Dap		= 1<<0,	Drlock		= 1<<1,	Edd		= 1<<2, 	/* bios calls: int 0x13 disk services */	Biosinit	= 0,		/* initialise disk & floppy ctlrs */	Biosdrvsts,	Bioschsrdsects,	Biosdrvparam	= 8,	Biosctlrinit,	Biosreset	=  0xd,		/* reset disk */	Biosdrvrdy	= 0x10,	Biosdrvtype	= 0x15,	Biosckext	= 0x41,	Biosrdsect,	Biosedrvparam	= 0x48, 	/* disk types */	Typenone	= 0,	Typedisk	= 3, 	/* magic numbers for bios calls */	Imok		= 0x55aa,	Youreok		= 0xaa55,}; struct Biosdrive {	int	ndevs;}; struct Biosdev {	Devbytes size;	Devbytes offset;	uchar	id;			/* drive number; e.g., 0x80 */	char	type;	ushort	sectsz;}; typedef struct Extread {		/* a device address packet */	uchar	size;	uchar	unused1;	uchar	nsects;	uchar	unused2;	union {		ulong	addr;		/* actual address (nominally seg:off) */		struct {			ushort	addroff;	/* :offset */			ushort	addrseg;	/* segment: */		};	};	uvlong	stsect;			/* starting sector */	/* from edd 3.0: */	uvlong	buffer;			/* instead of addr, if addr is ~0 */} Extread; typedef struct Edrvparam {	/* from edd 1.1 spec */	ushort	size;			/* max. buffer (struct) size */	ushort	flags;	ulong	physcyls;	ulong	physheads;	ulong	phystracksects;	uvlong	physsects;	ushort	sectsz;	/* pointer is required to be unaligned, bytes 26-29.  ick. *///	void	*dpte;			/* ~0ull: invalid */	uchar	dpte[4]; 	/* remainder from edd 3.0 spec */	ushort	key;			/* 0xbedd if present */	uchar	dpilen;	uchar	unused1;	ushort	unused2;	char	bustype[4];		/* "PCI" or "ISA" */	char	ifctype[8]; /* "ATA", "ATAPI", "SCSI", "USB", "1394", "FIBRE" */	uvlong	ifcpath;	uvlong	devpath;	uchar	unused3;	uchar	dpicksum;} Edrvparam; void	realmode(int intr, Ureg *ureg);		/* from trap.c */ int onlybios0;int biosinited; static Biosdev bdev[Maxdevs];static Biosdrive bdrive;static Ureg regs; static int	dreset(uchar drive);static Devbytes	extgetsize(Biosdev *);static Devsects	getsize(uchar drive, char *type);static int	islba(uchar drive); voidstopbiosload(void){	biosload = 0;	print("disabling bios loading\n");} /* convert ah error code to a string (just common cases) */static char *strerr(uchar err){	switch (err) {	case 0:		return "none";	case 0x80:		return "disk timeout";	default:		return "unknown";	}} /* * caller must zero or otherwise initialise *rp, * other than ax, bx, dx, si & ds. */static intbiosdiskcall(Ureg *up, uchar op, ulong bx, ulong dx, ulong si){	int s;	uchar err; 	s = splhi();		/* don't let the bios call be interrupted */ 	up->ax = op << 8;	up->bx = bx;	up->dx = dx;		/* often drive id */	/*	 * ensure that dap addr fits in a short.	 */	if((si & 0xffff0000) != 0)		print("biosdiskcall: dap address %#lux not a short\n", si); 	/* assume si is in first 64K */	if((si & 0xffff0000) != ((si + 512 - 1) & 0xffff0000))		print("biosdiskcall: dap address %#lux too near segment boundary\n",			si);	up->si = si;		/* ds:si forms data access packet addr */	up->ds = 0;	up->di = 0; 	/*	 * *up is copied into low memory (realmoderegs) and thence into	 * the machine registers before the BIOS call, and the registers are	 * copied into realmoderegs and thence into *up after.	 *	 * realmode loads these registers: di, si, ax, bx, cx, dx, ds, es.	 */	realmode(0x13, up); 	splx(s); 	if (up->flags & CF) {		if (Debug && dx == Baseid) {			err = up->ax >> 8;			print("\nbiosdiskcall: int 0x13 op %#ux drive %#lux "				"failed, ah error code %#ux (%s)\n",				op, dx, err, strerr(err));		}		return -1;	}	return 0;} /* * Find out what the bios knows about devices. * our boot device could be usb; ghod only knows where it will appear. */intbiosinit(void){	int devid, lba, mask, lastbit, ndrive;	Devbytes size;	char type;	Biosdev *bdp;	static int beenhere; 	delay(Pause);		/* pause to read the screen (DEBUG) */ 	/*	 * 9pxeload can't use bios int 13 calls; they wedge the machine.	 */	if (pxe || !biosload || onlybios0 || biosinited || beenhere)		return 0;	beenhere = 1; 	ndrive = *(uchar *)KADDR(0x475);	if (Debug)		print("bios claims %d drive(s)\n", ndrive);	mask = lastbit = 0;	for (devid = Baseid; devid < (1 << 8) && bdrive.ndevs < Maxdevs;	     devid++) {		lba = islba(devid);		if (lba < 0)			break; 		/* don't reset; it seems to hang the bios */		if(!lba /* || devid != Baseid && dreset(devid) < 0 */ )			continue;		type = Typenone;		if (getsize(devid, &type) == 0)		/* no device */			continue;		lastbit = 1 << bdrive.ndevs;		mask |= lastbit;		bdp = &bdev[bdrive.ndevs];		bdp->id = devid;		bdp->type = type;		size = extgetsize(bdp);		bdp->size = size;		print("bios%d: drive %#ux: %,llud bytes, type %d\n",			bdrive.ndevs, devid, size, type);		bdrive.ndevs++;	}	USED(lastbit);//	islba(Baseid);	/* do a successful operation to make bios happy again */ 	if (Debug && ndrive != bdrive.ndevs)		print("bios: ndrive %d != bdrive.ndevs %d\n",			ndrive, bdrive.ndevs);	if (ndrive < bdrive.ndevs)		bdrive.ndevs = ndrive;		/* use smaller estimate */ 	/*	 * some bioses seem to only be able to read from drive number 0x80	 * and certainly can't read from the highest drive number when we	 * call them, even if there is only one.	 */	if (bdrive.ndevs > 0)		biosinited = 1;	delay(Pause);		/* pause to read the screen (DEBUG) */ 	return mask;} voidbiosinitdev(int i, char *name){	if(i >= bdrive.ndevs)		panic("biosinitdev");	sprint(name, "bios%d", i);} voidbiosprintdevs(int i){	if(i >= bdrive.ndevs){		print("got a print for %d, only got %d\n", i, bdrive.ndevs);		panic("biosprintdevs");	}	print(" bios%d", i);} intbiosboot(int dev, char *file, Boot *b){	Fs *fs; 	if(strncmp(file, "dos!", 4) == 0)		file += 4;	if(strchr(file, '!') != nil || strcmp(file, "") == 0) {		print("syntax is bios0!file\n");		return -1;	} 	fs = biosgetfspart(dev, "9fat", 1);	if(fs == nil)		return -1;	return fsboot(fs, file, b);} static voiddump(void *addr, int wds){	unsigned i;	ulong *p = addr; 	for (i = 0; i < wds; i++)		print("%lux ", p[i]);		if (i % 8 == 7)			print("\n");	print("\n");} /* realmode loads these registers: di, si, ax, bx, cx, dx, ds, es */static voidinitrealregs(Ureg *up){	memset(up, 0, sizeof *up);} /* read n bytes at sector offset into a from drive id */longsectread(Biosdev *bdp, void *a, long n, Devsects offset){	uchar *biosparam, *cp;	Extread *erp; 	if(n < 0 || n > bdp->sectsz)		return -1;	if(Debug)		/* scribble on the buffer to provoke trouble */		memset((uchar *)BIOSXCHG, 'r', bdp->sectsz); 	/* space for a big, optical-size sector, just in case... */	biosparam = (uchar *)BIOSXCHG + 2*1024; 	/* read into BIOSXCHG */	erp = (Extread *)biosparam;	memset(erp, 0, sizeof *erp);	erp->size = sizeof *erp;	erp->nsects = 1;	erp->stsect = offset;	erp->buffer = PADDR(BIOSXCHG); 	erp->addr = PADDR(BIOSXCHG);	erp->addroff = PADDR(BIOSXCHG);		/* pedantic seg:off */	erp->addrseg = 0;	/*	 * ensure that buffer addr fits in a short.	 */	if((erp->addr & 0xffff0000) != 0)		print("sectread: address %#lux not a short\n", erp->addr);	if((erp->addr & 0xffff0000) != ((erp->addr + 512 - 1) & 0xffff0000))		print("sectread: address %#lux too near seg boundary\n",			erp->addr);	if (Debug)		print("reading drive %#ux sector %lld -> %#lux...",			bdp->id, offset, erp->addr); 	initrealregs(&regs);//	regs.es = erp->addr >> 16;	regs.es = 0;	delay(Pause);			/* pause to read the screen (DEBUG) */	/*	 * int 13 read sector expects, buffer seg in di?,	 * dap (erp) in si, 0x42 in ah, drive in dl.	 */	if (biosdiskcall(&regs, Biosrdsect, erp->addr, bdp->id, PADDR(erp)) < 0) {		print("sectread: bios failed to read %ld @ sector %lld of %#ux\n",			n, offset, bdp->id);		stopbiosload();		/* stop trying before we wedge */		return -1;	}	if (Debug)		print("OK\n"); 	/* copy into caller's buffer */	memmove(a, (char *)BIOSXCHG, n);	if(0 && Debug){		cp = (uchar *)BIOSXCHG;		print("-%ux %ux %ux %ux--%16.16s-\n",			cp[0], cp[1], cp[2], cp[3], (char *)cp + 480);	}	delay(Pause);		/* pause to read the screen (DEBUG) */	return n;} /* not tested yet. */static intdreset(uchar drive){	print("devbios: resetting %#ux...", drive);	initrealregs(&regs);	if (biosdiskcall(&regs, Biosinit, 0, drive, 0) < 0)		print("failed");	print("\n");	return regs.ax? -1: 0;		/* ax!=0 on error */} static intislba(uchar drive){	initrealregs(&regs);	if (biosdiskcall(&regs, Biosckext, Imok, drive, 0) < 0)		/*		 * we have an old bios without extensions, in theory.		 * in practice, there may just be no drive for this number.		 */		return -1;	if(regs.bx != Youreok){		print("islba: buggy bios: drive %#ux extension check returned "			"%lux in bx\n", drive, regs.bx);		stopbiosload();		return -1;	}	if (Debug) {		print("islba: drive %#ux extensions version %d.%d cx %#lux\n",			drive, (uchar)(regs.ax >> 8), (uchar)regs.ax, regs.cx);		print("\tsubsets supported:");		if (regs.cx & Dap)			print(" disk access;");		if (regs.cx & Drlock)			print(" drive locking;");		if (regs.cx & Edd)			print(" enhanced disk support;");		print("\n");	}	delay(Pause);			/* pause to read the screen (DEBUG) */	return regs.cx & Dap;} /* * works so-so... some floppies are 0x80+x when they shouldn't be, * and report lba even if they cannot... */static Devsectsgetsize(uchar id, char *typep){	int dtype; 	initrealregs(&regs);	if (biosdiskcall(&regs, Biosdrvtype, Imok, id, 0) < 0)		return 0; 	*typep = dtype = (ushort)regs.ax >> 8;	if(dtype == Typenone){		print("no such device %#ux of type %d\n", id, dtype);		return 0;	}	if(dtype != Typedisk){		print("non-disk device %#ux of type %d\n", id, dtype);		return 0;	}	return (ushort)regs.cx | regs.dx << 16;} /* extended get size */static Devbytesextgetsize(Biosdev *bdp){	Edrvparam *edp; 	edp = (Edrvparam *)BIOSXCHG;	memset(edp, 0, sizeof *edp);	edp->size = sizeof *edp;	edp->dpilen = 36; 	initrealregs(&regs);	if (biosdiskcall(&regs, Biosedrvparam, 0, bdp->id, PADDR(edp)) < 0)		return 0;		/* old bios without extensions */	if(Debug) {		print("extgetsize: drive %#ux info flags %#ux",			bdp->id, edp->flags);		if (edp->key == 0xbedd)			print(" %.4s %.8s", edp->bustype, edp->ifctype);		print("\n");	}	if (edp->sectsz <= 0) {		print("extgetsize: drive %#ux: sector size <= 0\n", bdp->id);		edp->sectsz = 1;		/* don't divide by 0 */	}	bdp->sectsz = edp->sectsz;	return edp->physsects * edp->sectsz;} longbiosread(Fs *fs, void *a, long n){	int want, got, part;	long totnr, stuck;	Devbytes offset;	Biosdev *bdp; 	if(!biosload || fs->dev > bdrive.ndevs)		return -1;	if (n <= 0)		return n;	bdp = &bdev[fs->dev];

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