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Fix metal bugs so deathstar.com runs in qemu (#20)

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- Remove XD bit in page tables
- Fix cylinder+head+sector arithmetic
- Implement fstat() for serial file descriptors on metal

Here's how to boot an Actually Portable Executable in QEMU:

    make -j12 o//tool/viz/deathstar.com
    qemu-system-x86_64 -serial stdio -fda o//tool/viz/deathstar.com

Here's a screenshot of DEATHSTAR.COM booted in QEMU:
https://justine.lol/cosmopolitan/cosmo-metal-qemu.png

Thus metal support is in much better shape now, but still incomplete.
Only a few system calls have been polyfilled. To figure out which ones
your program needs, simply boot it in the blinkenlights emulator with a
breakpoint, and press CTRL-C to continue to the system call breakpoint.
If it doesn't break then you should be good. (Note: to emulate normally
you can press 'c' and use CTRL-T and ALT-T to tune the speed.)

    m=tiny
    make -j12 SILENT=0 MODE=$m          \
      o/$m/tool/build/blinkenlights.com \
      o/$m/tool/viz/deathstar.com
    o/$m/tool/build/blinkenlights.com   \
      -r -t -b systemfive.linux         \
      o/$m/tool/viz/deathstar.com

Thank @Theldus for the bug report that made this change possible.
Fixes #20 which explains this change further.
This commit is contained in:
Justine Tunney 2021-01-16 17:52:15 -08:00
parent 58d9659d53
commit f0600a898c
13 changed files with 182 additions and 119 deletions
Download patch file Download diff file Expand all files Collapse all files

21
tool/build/blinkenlights.c
View file

@ -1789,14 +1789,14 @@ static void OnDiskServiceBadCommand(void) {
}
static void OnDiskServiceGetParams(void) {
size_t lastsector, lasttrack, lasthead;
lasthead = GetLastIndex(elf->mapsize, 512 * 63 * 1024, 0, 255);
lasttrack = GetLastIndex(elf->mapsize, 512 * 63, 0, 1023);
size_t lastsector, lastcylinder, lasthead;
lastcylinder = GetLastIndex(elf->mapsize, 512 * 63 * 255, 0, 1023);
lasthead = GetLastIndex(elf->mapsize, 512 * 63, 0, 255);
lastsector = GetLastIndex(elf->mapsize, 512, 1, 63);
m->dx[0] = 1;
m->dx[1] = lasthead;
m->cx[0] = lasttrack >> 8 << 6 | lastsector;
m->cx[1] = lasttrack;
m->cx[0] = lastcylinder >> 8 << 6 | lastsector;
m->cx[1] = lastcylinder;
m->ax[1] = 0;
Write64(m->es, 0);
Write16(m->di, 0);
@ -1806,18 +1806,17 @@ static void OnDiskServiceGetParams(void) {
static void OnDiskServiceReadSectors(void) {
static int x;
uint64_t addr, size;
int64_t sectors, drive, head, track, sector, offset;
int64_t sectors, drive, head, cylinder, sector, offset;
sectors = m->ax[0];
drive = m->dx[0];
head = m->dx[1];
track = (m->cx[0] & 0b11000000) << 2 | m->cx[1];
cylinder = (m->cx[0] & 0b11000000) << 2 | m->cx[1];
sector = (m->cx[0] & 0b00111111) - 1;
offset = head * track * sector * 512;
size = sectors * 512;
offset = sector * 512 + track * 512 * 63 + head * 512 * 63 * 1024;
offset = sector * 512 + head * 512 * 63 + cylinder * 512 * 63 * 255;
VERBOSEF("bios read sectors %d "
"@ sector %ld track %ld head %ld drive %ld offset %#lx",
sectors, sector, track, head, drive, offset);
"@ sector %ld cylinder %ld head %ld drive %ld offset %#lx",
sectors, sector, cylinder, head, drive, offset);
if (0 <= sector && offset + size <= elf->mapsize) {
addr = Read64(m->es) + Read16(m->bx);
if (addr + size <= m->real.n) {