#include <thread.h>

#include <u.h>
#include <libc.h>
#include <thread.h>
#include <draw.h>
#include <libsec.h>
#include "dat.h"
#include "fns.h"
#include "x86.h"

static uchar hdr[8192];
static int fd;

extern int bootmodn;
extern char **bootmod;
extern int cmdlinen;
extern char **cmdlinev;
extern VgaMode *curmode, textmode;
extern uintptr fbaddr, fbsz;

static int elf64;

static int
biostype(Region *r)
{
return r->type >> 8 & 0xff;
}

static void *
pack(void *v, char *fmt, ...)
{
uchar *p;
va_list va;

p = v;
va_start(va, fmt);
for(; *fmt != 0; fmt++)
switch(*fmt){
case '.': p++; break;
case 's': PUT16(p, 0, va_arg(va, int)); p += 2; break;
case 'i': PUT32(p, 0, va_arg(va, u32int)); p += 4; break;
case 'v': PUT64(p, 0, va_arg(va, u64int)); p += 8; break;
case 'z': if(elf64) {PUT64(p, 0, va_arg(va, uintptr)); p += 8;} else {PUT32(p, 0, va_arg(va, uintptr)); p += 4;} break;
default: sysfatal("pack: unknown fmt character %c", *fmt);
}
va_end(va);
return p;
}

static int
putmmap(uchar *p0)
{
uchar *p;
Region *r;
int t;

p = p0;
for(r = mmap; r != nil; r = r->next){
t = biostype(r);
if(t == 0) continue;
if(gavail(p) < 24) sysfatal("out of guest memory");
p = pack(p, "ivvi", 20, (uvlong) r->start, (uvlong)(r->end - r->start), t);
}
return (uchar *) p - p0;
}

static int
putcmdline(uchar *p0)
{
int i;
char *p, *e;

if(cmdlinen == 0) return 0;
p = (char*)p0;
e = gend(p0);
if(p >= e) return 0;
for(i = 0; i < cmdlinen; i++){
p = strecpy(p, e, cmdlinev[i]);
if(i != cmdlinen - 1) *p++ = ' ';
}
return p - (char*)p0 + 1;
}

static int
putmods(uchar *p0)
{
int i, fd, rc;
u32int *p;
uchar *q;
char dummy;

if(bootmodn == 0) return 0;
p = (u32int*)p0;
q = (uchar*)(p + 4 * bootmodn);
for(i = 0; i < bootmodn; i++){
q = gptr(-(-gpa(q) & -BY2PG), 1);
if(q == nil) sysfatal("out of guest memory");
fd = open(bootmod[i], OREAD);
if(fd == -1) sysfatal("module open: %r");
p[0] = gpa(q);
rc = readn(fd, q, gavail(q));
if(rc < 0) sysfatal("module read: %r");
if(read(fd, &dummy, 1) == 1) sysfatal("out of guest memory");
close(fd);
q += rc;
p[1] = gpa(q);
p[2] = 0;
p[3] = 0;
p += 4;
}
bootmodn = ((uchar*)p - p0) / 16;
return q - p0;
}

static int
trymultiboot(void)
{
u32int *p, flags;
u32int header, load, loadend, bssend, entry;
u32int filestart;
uchar *gp;
uchar *modp;
int len;
int rc;

for(p = (u32int*)hdr; p < (u32int*)hdr + sizeof(hdr)/4; p++)
if(*p == 0x1badb002)
break;
if(p == (u32int*)hdr + sizeof(hdr)/4)
return 0;
if((u32int)(p[0] + p[1] + p[2]) != 0)
sysfatal("invalid multiboot checksum");
flags = p[1];
if((flags & 1<<16) == 0)
sysfatal("no size info in multiboot header");
header = p[3];
load = p[4];
loadend = p[5];
bssend = p[6];
entry = p[7];
filestart = (uchar*)p - hdr - (header - load);
gp = gptr(load, bssend != 0 ? bssend - load : loadend != 0 ? loadend - load : BY2PG);
if(gp == nil)
sysfatal("kernel image out of bounds");
seek(fd, filestart, 0);
if(loadend == 0){
rc = readn(fd, gp, gavail(gp));
if(rc <= 0) sysfatal("readn: %r");
loadend = load + rc;
}else{
rc = readn(fd, gp, loadend - load);
if(rc < 0) sysfatal("readn: %r");
if(rc < loadend - load) sysfatal("short kernel image");
}
if(bssend == 0) bssend = loadend;
bssend = -(-bssend & -BY2PG);
p = gptr(bssend, 128);
if(p == nil) sysfatal("no space for multiboot structure");
memset(p, 0, 128);
p[0] = 1<<0;
p[1] = gavail(gptr(0, 0)) >> 10;
if(p[1] > 640) p[1] = 640;
p[2] = gavail(gptr(1048576, 0)) >> 10;
modp = gptr(bssend + 128, 1);
if(modp == nil) sysfatal("out of guest memory");
len = putmmap(modp);
if(len != 0){
p[0] |= 1<<6;
p[11] = len;
p[12] = gpa(modp);
modp += len;
}
len = putcmdline(modp);
if(len != 0){
p[0] |= 1<<2;
p[4] = gpa(modp);
modp += len + 7 & -8;
}
len = putmods(modp);
if(len != 0){
p[0] |= 1<<3;
p[5] = bootmodn;
p[6] = gpa(modp);
modp += len + 7 & -8;
}

if(curmode != nil && curmode != &textmode){
int i, o, n;
u16int r, g, b;

o = 0;
r = g = b = 0;
for(i = 0; i < 4; i++){
n = curmode->chan >> 8*i & 0xf;
if(n == 0) continue;
switch(curmode->chan >> 4 + 8*i & 0xf){
case CRed: r = o | n<<8; break;
case CGreen: g = o | n<<8; break;
case CBlue: b = o | n<<8; break;
}
o += n;
}
p[0] |= 1<<12;
pack(&p[22], "viiiisss", (u64int)fbaddr,
curmode->hbytes, curmode->w, curmode->h,
chantodepth(curmode->chan) | 1<<8, r, g, b);
}

USED(modp);
rset(RPC, entry);
rset(RAX, 0x2badb002);
rset(RBX, bssend);
return 1;
}

typedef struct ELFHeader ELFHeader;
struct ELFHeader {
uintptr entry, phoff, shoff;
u32int flags;
u16int ehsize;
u16int phentsize, phnum;
u16int shentsize, shnum, shstrndx;
};
typedef struct ELFPHeader ELFPHeader;
struct ELFPHeader {
u32int type, flags;
uintptr offset, vaddr, paddr, filesz, memsz, align;
};
enum {
PT_NULL, PT_LOAD, PT_DYNAMIC, PT_INTERP, PT_NOTE,
PT_SHLIB, PT_PHDR, PT_TLS,
PT_GNU_EH_FRAME = 0x6474e550,
PT_GNU_RELRO = 0x6474e552,
PT_OPENBSD_RANDOMIZE = 0x65a3dbe6,
};
typedef struct ELFSHeader ELFSHeader;
struct ELFSHeader {
u32int iname, type;
uintptr flags, addr, offset, size;
u32int link, info;
uintptr addralign, entsize;
char *name;
};
enum {
SHT_SYMTAB = 2,
SHT_STRTAB = 3,
SHF_ALLOC = 2,
};
typedef struct ELFSymbol ELFSymbol;
struct ELFSymbol {
u32int iname;
uintptr addr, size;
u8int info, other;
u16int shndx;
char *name;
};
static ELFHeader eh;
static ELFPHeader *ph;
static ELFSHeader *sh;
static ELFSymbol *sym;
static int nsym;
static uintptr elfmax;

static u64int
elff(uchar **p, uchar *e, int sz)
{
u64int rc;

if(sz == -1)
sz = elf64 ? 8 : 4;
if(*p + sz > e){
fprint(2, "out of bounds: %#p > %#p", *p + sz, e);
return 0;
}
switch(sz){
case 1: rc = GET8(*p, 0); break;
case 2: rc = GET16(*p, 0); break;
case 3: case 4: rc = GET32(*p, 0); break;
default: rc = GET64(*p, 0); break;
}
*p += sz;
return rc;
}

static void
elfheader(ELFHeader *eh, uchar *p, uchar *e)
{
eh->entry = elff(&p, e, -1);
eh->phoff = elff(&p, e, -1);
eh->shoff = elff(&p, e, -1);
eh->flags = elff(&p, e, 4);
eh->ehsize = elff(&p, e, 2);
eh->phentsize = elff(&p, e, 2);
eh->phnum = elff(&p, e, 2);
eh->shentsize = elff(&p, e, 2);
eh->shnum = elff(&p, e, 2);
eh->shstrndx = elff(&p, e, 2);
}

static void
elfpheader(ELFPHeader *ph, uchar *p, uchar *e)
{
ph->type = elff(&p, e, 4);
if(elf64) ph->flags = elff(&p, e, 4);
ph->offset = elff(&p, e, -1);
ph->vaddr = elff(&p, e, -1);
ph->paddr = elff(&p, e, -1);
ph->filesz = elff(&p, e, -1);
ph->memsz = elff(&p, e, -1);
if(!elf64) ph->flags = elff(&p, e, 4);
ph->align = elff(&p, e, -1);
}

static void
elfsheader(ELFSHeader *sh, uchar *p, uchar *e)
{
sh->iname = elff(&p, e, 4);
sh->type = elff(&p, e, 4);
sh->flags = elff(&p, e, -1);
sh->addr = elff(&p, e, -1);
sh->offset = elff(&p, e, -1);
sh->size = elff(&p, e, -1);
sh->link = elff(&p, e, 4);
sh->info = elff(&p, e, 4);
sh->addralign = elff(&p, e, -1);
sh->entsize = elff(&p, e, -1);
}

static void
elfsymbol(ELFSymbol *s, uchar *p, uchar *e)
{
s->iname = elff(&p, e, 4);
if(elf64){
s->info = elff(&p, e, 1);
s->other = elff(&p, e, 1);
s->shndx = elff(&p, e, 2);
s->addr = elff(&p, e, -1);
s->size = elff(&p, e, -1);
}else{
s->addr = elff(&p, e, -1);
s->size = elff(&p, e, -1);
s->info = elff(&p, e, 1);
s->other = elff(&p, e, 1);
s->shndx = elff(&p, e, 2);
}
}

static void
epreadn(void *buf, ulong sz, vlong off, char *fn)
{
seek(fd, off, 0);
werrstr("eof");
if(readn(fd, buf, sz) < sz)
sysfatal("%s: read: %r", fn);
}

static int
elfheaders(void)
{
uchar *buf;
int i;
ELFSHeader *s;

if(GET32(hdr, 0) != 0x464c457f) return 0;
if(hdr[5] != 1 || hdr[6] != 1 || hdr[0x14] != 1) return 0;
switch(hdr[4]){
case 1: elf64 = 0; break;
case 2: elf64 = 1; if(sizeof(uintptr) == 4) sysfatal("64-bit binaries not supported on 32-bit host"); break;
default: return 0;
}
elfheader(&eh, hdr + 0x18, hdr + sizeof(hdr));
buf = emalloc(eh.phentsize > eh.shentsize ? eh.phentsize : eh.shentsize);
ph = emalloc(sizeof(ELFPHeader) * eh.phnum);
for(i = 0; i < eh.phnum; i++){
epreadn(buf, eh.phentsize, eh.phoff + i * eh.phentsize, "elfheaders");
elfpheader(&ph[i], buf, buf + eh.phentsize);
}
sh = emalloc(sizeof(ELFSHeader) * eh.shnum);
for(i = 0; i < eh.shnum; i++){
epreadn(buf, eh.shentsize, eh.shoff + i * eh.shentsize, "elfheaders");
elfsheader(&sh[i], buf, buf + eh.shentsize);
}
free(buf);

if(eh.shstrndx != 0 && eh.shstrndx < eh.shnum){
s = &sh[eh.shstrndx];
if(s->type != SHT_STRTAB)
sysfatal("elfheaders: section string table is not a string table");
buf = emalloc(s->size + 1);
epreadn(buf, s->size, s->offset, "elfheaders");
for(i = 0; i < eh.shnum; i++){
if(sh[i].iname < s->size)
sh[i].name = (char *) &buf[sh[i].iname];
}
}

return 1;
}

static void
elfdata(void)
{
int i;
void *v;

for(i = 0; i < eh.phnum; i++){
switch(ph[i].type){
case PT_NULL:
case PT_GNU_RELRO:
case PT_NOTE:
continue;
case PT_DYNAMIC:
case PT_INTERP:
sysfatal("elf: dynamically linked");
default:
sysfatal("elf: unknown program header type %#ux", (int)ph[i].type);
case PT_LOAD:
case PT_PHDR:
case PT_OPENBSD_RANDOMIZE:
break;
}
v = gptr(ph[i].paddr, ph[i].memsz);
if(v == nil)
sysfatal("invalid address %#p (length=%#p) in elf", (void*)ph[i].paddr, (void*)ph[i].memsz);
if(ph[i].type == PT_OPENBSD_RANDOMIZE)
genrandom(v, ph[i].memsz);
else{
if(ph[i].filesz > ph[i].memsz)
sysfatal("elf: header entry shorter in memory than in the file (%#p < %#p)", (void*)ph[i].memsz, (void*)ph[i].filesz);
if(ph[i].filesz != 0)
epreadn(v, ph[i].filesz, ph[i].offset, "elfdata");
if(ph[i].filesz < ph[i].memsz)
memset((uchar*)v + ph[i].filesz, 0, ph[i].memsz - ph[i].filesz);
}
if(ph[i].paddr + ph[i].memsz > elfmax)
elfmax = ph[i].paddr + ph[i].memsz;
}
}

static int
elfsymbols(void)
{
ELFSHeader *s, *sy, *st;
char *str;
uchar *buf, *p;
int i;

sy = nil;
st = nil;
for(s = sh; s < sh + eh.shnum; s++){
if(s->type == SHT_SYMTAB && s->name != nil && strcmp(s->name, ".symtab") == 0)
sy = s;
if(s->type == SHT_STRTAB && s->name != nil && strcmp(s->name, ".strtab") == 0)
st = s;
}
if(sy == nil || st == nil)
return 0;
if(sy->entsize == 0 || (sy->size % sy->entsize) != 0)
sysfatal("symbol section: invalid headers");
str = emalloc(st->size);
epreadn(str, st->size, st->offset, "elfsymbols");
buf = emalloc(sy->size);
epreadn(buf, sy->size, sy->offset, "elfsymbols");
nsym = sy->size / sy->entsize;
sym = emalloc(sizeof(ELFSymbol) * nsym);
for(i = 0; i < nsym; i++){
p = buf + i * sy->entsize;
elfsymbol(sym + i, p, p + sy->entsize);
if(sym[i].iname < st->size)
sym[i].name = &str[sym[i].iname];
}
free(buf);
return 1;
}

static ELFSymbol *
elfsym(char *n)
{
ELFSymbol *s;

for(s = sym; s < sym + nsym; s++)
if(s->name != nil && strcmp(s->name, n) == 0)
return s;
return nil;
}

static void *
symaddr(ELFSymbol *s)
{
ELFPHeader *p;

if(s == nil) return nil;
for(p = ph; p < ph + eh.phnum; p++)
if(s->addr >= p->vaddr && s->addr < p->vaddr + p->memsz)
return gptr(p->paddr + (s->addr - p->vaddr), s->size);
return nil;
}

static uchar *obsdarg, *obsdarg0, *obsdargnext;
static int obsdarglen;
static int obsdconsdev = 12 << 8, obsddbcons = -1, obsdbootdev;

enum {
BOOTARG_MEMMAP,
BOOTARG_DISKINFO,
BOOTARG_APMINFO,
BOOTARG_CKSUMLEN,
BOOTARG_PCIINFO,
BOOTARG_CONSDEV,
BOOTARG_SMPINFO,
BOOTARG_BOOTMAC,
BOOTARG_DDB,
BOOTARG_BOOTDUID,
BOOTARG_BOOTSR,
BOOTARG_EFIINFO,
BOOTARG_END = -1,
};

static void
obsdelfload(void)
{
void *v, *w, *hdrfix;
int shentsize;
int saddr;
ELFSHeader *s;
uintptr off;

saddr = elf64 ? 8 : 4;
elfmax = -(-elfmax & -saddr);
v = gptr(elfmax, eh.ehsize);
if(v == nil)
space: sysfatal("out of space for kernel");
epreadn(v, eh.ehsize, 0, "obsdelfload");
elfmax += -(-eh.ehsize & -saddr);
hdrfix = (uchar*)v + (elf64 ? 0x20 : 0x1c);

shentsize = 40 + 24*elf64;
v = gptr(elfmax, shentsize * eh.shnum);
if(v == nil) goto space;
off = shentsize * eh.shnum;
elfmax += off;
off += -(-eh.ehsize & -saddr);
for(s = sh; s < sh + eh.shnum; s++)
if(s->type == SHT_SYMTAB || s->type == SHT_STRTAB ||
s->name != nil && (strcmp(s->name, ".debug_line") == 0 || strcmp(s->name, ".SUNW_ctf") == 0)){
w = gptr(elfmax, s->size);
if(w == nil) goto space;
epreadn(w, s->size, s->offset, "obsdelfload");
v = pack(v, "iizzzziizz",
s->iname, s->type, s->flags | SHF_ALLOC, (uintptr)0,
off, s->size, s->link, s->info, s->addralign, s->entsize);
elfmax += -(-s->size & -saddr);
off += -(-s->size & -saddr);
}else{
memset(v, 0, shentsize);
v = (uchar*)v + shentsize;
}
pack(hdrfix, "zz......sss", (uintptr)0, -(-eh.ehsize & -saddr), 0, 0, shentsize);
}

#define obsdpack(...) (obsdarg = pack(obsdarg, __VA_ARGS__))

static void
obsdstart(int type)
{
obsdarg0 = obsdarg;
PUT32(obsdarg, 0, type);
PUT32(obsdarg, 8, 0); /* next */
obsdarg += 12;
}

static void
obsdend(void)
{
if(obsdarg == obsdarg0 + 12) obsdarg += 4;
PUT32(obsdarg0, 4, obsdarg - obsdarg0); /* size */
obsdarglen += obsdarg - obsdarg0;
PUT32(obsdargnext, 0, gpa(obsdarg0));
obsdargnext = obsdarg0 + 8;
obsdarg0 = nil;
}

static void
obsdfb(void)
{
int i, s, p;
u32int r, g, b, a, m;

if(curmode == nil || curmode == &textmode) return;
p = r = g = b = a = 0;
for(i = 0; i < 4; i++){
s = curmode->chan >> 8 * i & 0xf;
if(s == 0) continue;
m = (1<<s)-1 << p;
p += s;
switch(curmode->chan >> 4 + 8 * i & 0xf){
case CRed: r |= m; break;
case CGreen: g |= m; break;
case CBlue: b |= m; break;
case CAlpha: case CIgnore: a |= m; break;
default: return;
}
}
obsdstart(BOOTARG_EFIINFO);
obsdpack("vvvviiiiiii", 0ULL, 0ULL, (uvlong)fbaddr, (uvlong)fbsz, curmode->h, curmode->w, curmode->w, r, g, b, a);
obsdend();
}

static void
obsdargs(void)
{
Region *r;
int t;

obsdstart(BOOTARG_MEMMAP);
for(r = mmap; r != nil; r = r->next){
t = biostype(r);
if(t == 0) continue;
obsdpack("vvi", (uvlong)r->start, (uvlong)(r->end - r->start), t);
}
obsdpack("vvi", 0ULL, 0ULL, 0);
obsdend();
obsdstart(BOOTARG_CONSDEV); obsdpack("iiii", obsdconsdev, -1, -1, 0); obsdend();
if(obsddbcons != -1){
obsdstart(BOOTARG_DDB); obsdpack("i", obsddbcons); obsdend();
}
obsdfb();
obsdstart(BOOTARG_END); obsdend();
}

static int
obsdcmdline(int argc, char **argv)
{
char *p;
char *q, *r;
int howto;

howto = 0;
while(argc-- > 0){
p = *argv++;
if(*p == '-'){
while(*++p != 0)
switch(*p){
case 'a': howto |= 0x0001; break; /* RB_ASKNAME */
case 's': howto |= 0x0002; break; /* RB_SINGLE */
case 'd': howto |= 0x0040; break; /* RB_DDB */
case 'c': howto |= 0x0400; break; /* RB_CONFIG */
default: goto usage;
}
continue;
}
q = strchr(p, '=');
if(q == nil) goto usage;
*q++ = 0;
if(strcmp(p, "device") == 0){
obsdbootdev = 0;
switch(*q){
case 'w': break;
case 'f': obsdbootdev = 2; break;
case 's': obsdbootdev = 4; break;
case 'c': obsdbootdev = 6; break;
case 'r': obsdbootdev = 17; break;
case 'v': obsdbootdev = 14; if(*++q != 'n') goto nodev; break;
default: nodev: sysfatal("invalid device");
}
if(*++q != 'd') goto nodev;
obsdbootdev |= strtoul(++q, &r, 10) << 16;
if(r == q || (obsdbootdev & 0xfff00000) != 0) goto nodev;
if(*r < 'a' || *r > 'p') goto nodev;
obsdbootdev |= *r - 'a' << 8;
if(*++r != 0) goto nodev;
obsdbootdev |= 0xa0000000;
}else if(strcmp(p, "tty") == 0){
if(strcmp(q, "com0") == 0)
obsdconsdev = 8 << 8;
else if(strcmp(q, "com1") == 0)
obsdconsdev = 8 << 8 | 1;
else if(strcmp(q, "pc0") == 0)
obsdconsdev = 12 << 8;
else
sysfatal("tty must be one of com0, com1, pc0");
}else if(strcmp(p, "db_console") == 0){
if(strcmp(q, "on") == 0)
obsddbcons = 1;
else if(strcmp(q, "off") == 0)
obsddbcons = 0;
else
sysfatal("db_console must be one of on, off");
}else goto usage;
}
return howto;
usage:
fprint(2, "openbsd cmdline usage: kernel [-asdc] [var=value ...]\nsupported vars: device tty db_console\n");
threadexitsall("usage");
return 0;
}

static int
obsdload(void)
{
int sp;
int howto;
uchar *v;

obsdelfload();
sp = 0xfffc;
sp -= 36;
v = gptr(sp, 36);
howto = obsdcmdline(cmdlinen, cmdlinev);
assert(v != nil);
PUT32(v, 4, howto); /* howto */
PUT32(v, 8, obsdbootdev); /* bootdev */
PUT32(v, 12, 0xa); /* bootapiver */
PUT32(v, 16, elfmax); /* esym */
PUT32(v, 20, 0); /* extmem */
PUT32(v, 24, 0); /* cnvmem */
PUT32(v, 32, 0); /* bootargv */
obsdarg = gptr(0x10000, 4096);
assert(obsdarg != nil);
obsdargnext = &v[32]; /* bootargv */
obsdargs();
assert(obsdarg0 == nil);
PUT32(v, 28, obsdarglen); /* bootargc */
rset(RSP, sp);
rset(RPC, (u32int)eh.entry & 0x0fffffff);
return 1;
}

static int
tryelf(void)
{
char *s;

if(!elfheaders()) return 0;
elfdata();
if(!elfsymbols()) return 0;
s = symaddr(elfsym("ostype"));
if(s != nil && strcmp(s, "OpenBSD") == 0)
return obsdload();
return 0;
}

static void
linuxbootmod(char *fn, void *zp, u32int kend)
{
u32int addr;
uintptr memend;
int fd;
vlong sz;
void *v;
int rc;

fd = open(fn, OREAD);
if(fd < 0) sysfatal("linux: initrd: open: %r");
sz = seek(fd, 0, 2);
if(sz < 0) sysfatal("linux: initrd: seek: %r");
if(sz == 0) sysfatal("linux: empty initrd");
addr = GET32(zp, 0x22c);
memend = (1<<20) + gavail(gptr(1<<20, 0));
if(addr >= memend) addr = memend - 1;
if((addr - (sz - 1) & -4) < kend) sysfatal("linux: no room for initrd");
addr = addr - (sz - 1) & -4;
v = gptr(addr, sz);
if(v == nil) sysfatal("linux: initrd: gptr failed");
seek(fd, 0, 0);
rc = readn(fd, v, sz);
if(rc < 0) sysfatal("linux: initrd: read: %r");
if(rc < sz) sysfatal("linux: initrd: short read");
close(fd);
PUT32(zp, 0x218, addr);
PUT32(zp, 0x21C, sz);
}

static void
linuxscreeninfo(void *zp)
{
extern VgaMode *curmode, textmode;
extern uintptr fbaddr, fbsz;
uintptr extmem;
int i, p, s;

extmem = gavail(gptr(1<<20, 0)) >> 10;
if(extmem >= 65535) extmem = 65535;
PUT16(zp, 0x02, extmem);

if(curmode == nil) return;
if(curmode == &textmode){
PUT8(zp, 0x06, 3); /* mode 3 */
PUT8(zp, 0x07, 80); /* 80 cols */
PUT8(zp, 0x0e, 25); /* 25 rows */
PUT8(zp, 0x0f, 0x22); /* VGA */
PUT16(zp, 0x10, 16); /* characters are 16 pixels high */
}else{
PUT8(zp, 0x0f, 0x23); /* VESA linear framebuffer */
PUT16(zp, 0x12, curmode->w);
PUT16(zp, 0x14, curmode->h);
PUT16(zp, 0x16, chantodepth(curmode->chan));
PUT32(zp, 0x18, fbaddr);
PUT32(zp, 0x1C, fbsz);
PUT16(zp, 0x24, curmode->hbytes);
for(i = 0, p = 0; i < 4; i++){
s = curmode->chan >> 8 * i & 15;
if(s == 0) continue;
switch(curmode->chan >> 8 * i + 4 & 15){
case CRed: PUT16(zp, 0x26, s | p << 8); break;
case CGreen: PUT16(zp, 0x28, s | p << 8); break;
case CBlue: PUT16(zp, 0x2a, s | p << 8); break;
case CAlpha: case CIgnore: PUT16(zp, 0x2c, s | p << 8); ; break;
}
p += s;
}
PUT16(zp, 0x34, 1<<0|1<<1|1<<3|1<<4|1<<5|1<<6|1<<7); /* attributes */
}
}

static void
linuxgdt(void *v)
{
u32int base;

base = gpa(v);
rset("gdtrbase", base);
v = pack(v, "vvvv", 0, 0,
GDTBASE(0) | GDTLIM(-1) | GDTRX | GDTG | GDTP | GDT32,
GDTBASE(0) | GDTLIM(-1) | GDTRW | GDTG | GDTP | GDT32
);
rset("gdtrlimit", gpa(v) - base - 1);
rset("cs", 0x10);
rset("ds", 0x18);
rset("es", 0x18);
rset("ss", 0x18);
}

static void
linuxe820(uchar *zp)
{
Region *r;
uchar *v;
int t;
int n;

v = zp + 0x2d0;
n = 1;
for(r = mmap; r != nil; r = r->next){
t = biostype(r);
if(t == 0) continue;
v = pack(v, "vvi", r->start, r->end - r->start, t);
n++;
}
PUT8(zp, 0x1e8, n);
}

static int
trylinux(void)
{
char buf[1024];
u8int loadflags;
u16int version;
uchar *zp;
void *v;
u32int ncmdline, cmdlinemax, syssize, setupsects;

seek(fd, 0, 0);
if(readn(fd, buf, sizeof(buf)) < 1024) return 0;
if(GET16(buf, 0x1FE) != 0xAA55 || GET32(buf, 0x202) != 0x53726448) return 0;
version = GET16(buf, 0x206);
if(version < 0x206){
vmerror("linux: kernel too old (boot protocol version %d.%.2d, needs to be 2.06 or newer)", version >> 8, version & 0xff);
return 0;
}
loadflags = GET8(buf, 0x211);
if((loadflags & 1) == 0){
vmerror("linux: zImage is not supported");
return 0;
}
zp = gptr(0x1000, 0x1000);
if(zp == nil) sysfatal("linux: gptr for zeropage failed");
rset(RSI, 0x1000);
memset(zp, 0, 0x1000);
memmove(zp + 0x1f1, buf + 0x1f1, 0x202 + GET8(buf, 0x201) - 0x1f1);
setupsects = GET8(zp, 0x1F1);
if(setupsects == 0) setupsects = 4;
syssize = GET32(zp, 0x1F4);
cmdlinemax = GET32(zp, 0x238);

v = gptr(1<<20, syssize << 4);
if(v == nil) sysfatal("linux: not enough room for kernel");
epreadn(v, syssize << 4, (setupsects + 1) * 512, "trylinux");

v = gptr(0x20000, 1);
if(v == nil) sysfatal("linux: gptr for cmdline failed");
ncmdline = putcmdline(v);
if(ncmdline == 0)
*(uchar*)v = 0;
else
if(ncmdline - 1 > cmdlinemax) sysfatal("linux: cmdline too long (%d > %d)", ncmdline, cmdlinemax);
PUT32(zp, 0x228, 0x20000);

switch(bootmodn){
case 0: break;
default:
vmerror("linux: ignoring extra boot modules (only one supported)");
/* wet floor */
case 1:
linuxbootmod(*bootmod, zp, (1<<20) + (syssize << 4));
}

linuxscreeninfo(zp);
v = gptr(0x3000, 256);
if(v == nil) sysfatal("linux: gptr for gdt failed");
linuxgdt(v);

linuxe820(zp);

PUT16(zp, 0x1FA, 0xffff);
PUT8(zp, 0x210, 0xFF); /* bootloader ID */
PUT8(zp, 0x211, loadflags | 0x80); /* kernel can use heap */

PUT32(zp, 0x224, 0xfe00); /* kernel can use full segment */
rset(RPC, GET32(zp, 0x214));
rset(RBP, 0);
rset(RDI, 0);
rset(RBX, 0);
return 1;
}

void
loadkernel(char *fn)
{
fd = open(fn, OREAD);
if(fd < 0) sysfatal("open: %r");
if(readn(fd, hdr, sizeof(hdr)) <= 0)
sysfatal("readn: %r");
if(trymultiboot())
goto done;
if(tryelf())
goto done;
if(trylinux())
goto done;
sysfatal("%s: unknown format", fn);
done:
close(fd);
}