arti/vt1200
1
0 Fork 1
mirror of https://git.k-space.ee/arti/vt1200.git synced 2026-10-31 12:05:05 +02:00
Code Wiki Activity
Files
0563cb08e87fbc22fecc5da5d31cb0e5dc7609de
vt1200/harness/udpstream/lance_cmd.c
T
arti 0563cb08e8 udpstream: LANCE command payload -- peek/poke/jump/reboot, benchmark, driver-matched RX 
lance_cmd.c is a payload that drives the LANCE with its own code (no ROM
calls) and answers a command protocol on ethertype 0x88B6, so a unit whose
chip we have taken over can still be inspected:

  read (peek), stats, poke, jump, reboot

The reply path was dead for a while and the cause was not the chip: the RX
ring had been grown to 16 entries (0x3020..0x309F) while TXR stayed at
0x3060, so all eight TX descriptors lay inside the RX ring.  The chip's RX
write-back set OWN in what we believed were TX descriptors, and every reply
was discarded by transmit_poll() as "owned but not start of packet"
(r 00309A 8000 / w 00309A 0000 in the DMA log).  TX ring moved to 0x30C0,
with a compile-time guard so the rings cannot overlap again.

Receive path aligned with the three drivers available locally (4.4BSD
pmax if_le.c, NetBSD am7990.c, Linux 7990.c):

  * STP *and* ENP required on one descriptor, else the frame is counted as
    chained and dropped rather than parsed from the middle of a buffer;
  * the 4-byte FCS the chip writes into the buffer is subtracted, as all
    three do (rmd3 - 4);
  * re-arm restores RMD2 and clears RMD3, ownership written last;
  * TX kick is TDMD|INEA (no reference driver re-writes STRT);
  * a TX slot still owned is skipped instead of clobbered.

RX buffers are 1526 B so a full 1514-byte MTU frame fits one descriptor;
1500 B would have chained it.

vtcmd.py drives all of it; bench-sweep.sh sweeps size x rate.  Measured on
the real VT1200 (10 Mbit half-duplex hub): 856-858 fps of 1514-byte frames
at 99.9-100% delivery, i.e. wire limited, and 1500 fps of 60-byte frames at
99.8-99.9%.  NETWORK_REPORT.md sections 68-72 record the evidence, including
the 64-descriptor build that died with an illegal opcode on the unit and was
reverted.
2026-10-30 16:57:15 +02:00

521 lines
19 KiB
C
Raw Blame History

/*
* lance.c -- LANCE loopback probe using LOW-MEMORY rings.
*
* The OS's own init block (pointer at bit 0x23E7A0 -> byte 0xF80 on a live
* boot) puts its rings at byte 0x0A80 / 0x0E80 and stores only the LENGTH in
* the ring words' bits 13-15 (0xE000 / 0xA000), with no address bits above 16.
* MAME's model packs address bits 16+ into that word; if the real C-LANCE does
* not, a high ring address like 0x380028 is seen as 0x0028. This payload
* therefore places the block, rings and buffers below 64 KB.
*
* Memory used (BYTE addresses, well below 64 KB):
* 0x3000 init block (24 B) 0x3020 RX ring (8 * 8 B) 0x3060 TX ring (8 B)
* 0x3100 TX frame (24 B) 0x3200 RX buffer (2048 B)
*
* Result cells at 0x018C8000 (32-bit): 0x160/0x180 CSR0 samples,
* 0x200 RX RMD1, 0x220 RX MCNT, 0x240 TX TMD1, 0x1A0 payload-found flag.
*
* Panel rows (real unit, 256-byte stride): y 670/700 = CSR0, 730 = TMD1,
* 760 = RMD1, 790 = MCNT; blocks y 850: left = payload returned, right = TX done.
*/
#define RAP 0x05900000
#define RDP 0x05800000
#define MARK 0x018D0000 /* after .text (which now reaches 0x018CACD0) */
#define VRAM_BASE 0x04000000
#define MODE_LOOP 0x0004
#define MODE_INTL 0x0040
#define CSR0_STOP 0x0004
#define CSR0_STRT 0x0002
#define CSR0_INIT 0x0001
#define CSR0_TDMD 0x0008
#define CSR0_IDON 0x0100
#define RMD1_OWN 0x8000
#define RMD1_ENP 0x0100
#define RMD1_STP 0x0200
#define TMD1_OWN 0x8000
#define TMD1_ENP 0x0100
#define TMD1_STP 0x0200
/* Memory layout (BYTE addresses; the rings are 8-byte descriptors):
*
* 0x3000 init block (12 words = 24 B)
* 0x3020 RX ring, 16 entries -> 0x3020..0x309F
* 0x30C0 TX ring, 8 entries -> 0x30C0..0x30FF
* 0x3180 TX buffer
* 0x4000 RX buffers, RXBUFLEN apart
*
* The TX ring used to sit at 0x3060, which was fine while the RX ring had 8
* entries (0x3020..0x305F) but silently overlapped once it grew to 16. The
* chip then set OWN in what we believed were our TX descriptors, so every
* reply was discarded as "owned but not start-of-packet" and never reached
* the wire. Keep the two rings apart: NRX*8 must not reach TXR.
*/
#define B(byte) ((unsigned int)(byte) * 8) /* bit address of a byte */
#define INITB B(0x3000)
#define RXR B(0x3020)
#define TXR B(0x30C0)
#define RXBUF B(0x3200)
#define TXBUF B(0x3180)
#define NRX 16
#define RXBUFLEN 1526 /* one full 1514-byte MTU frame + margin */
#define ETHCMD 0x88B6
/* Compile-time guard: the RX ring must end before the TX ring starts.
* (Bit addresses: NRX descriptors of 64 bits each.) Violating this is what
* broke the first version of this payload, and it fails silently at runtime. */
typedef char rx_tx_rings_do_not_overlap[(RXR + NRX * 64 <= TXR) ? 1 : -1];
/* Re-arm one RX descriptor the way NetBSD's am7990_rint() does: message count
* and length first, ownership last, so the chip cannot take the descriptor
* while its length field is stale. */
#define REARM_RX(i, buf) do { \
w16(RXR + (i) * 64 + 48, 0); \
w16(RXR + (i) * 64 + 32, (0x10000 - RXBUFLEN) & 0xFFFF); \
w16(RXR + (i) * 64 + 16, RMD1_OWN | (((buf) >> 16) & 0xFF)); \
} while (0)
#define RING_ENTRIES 8
static void cell(off, v)
unsigned int off, v;
{
*(unsigned int *)(MARK + off) = v;
}
static void w16(bit, v)
unsigned int bit, v;
{
*(unsigned short *)bit = v;
}
static unsigned int r16(bit)
unsigned int bit;
{
return *(unsigned short *)bit;
}
static unsigned int rb(bit)
unsigned int bit;
{
return *(unsigned char *)bit;
}
static void wb(bit, v)
unsigned int bit, v;
{
*(unsigned char *)bit = v;
}
static void rect(x, y, w, h, v)
unsigned int x, y, w, h, v;
{
unsigned int row, col;
for (row = 0; row < h; row++) {
for (col = 0; col < w; col = col + 8) {
*(unsigned char *)(VRAM_BASE + (y + row) * 2048 + x + col) = v;
}
}
}
static void bits16(x, y, v)
unsigned int x, y, v;
{
unsigned int b;
for (b = 0; b < 16; b++) {
rect(x + b * 30, y, 24, 24, (v & (1 << b)) ? 0xFF : 0x00);
}
}
static void dot(n)
unsigned int n;
{
rect(60, 650 + n * 44, 24, 24, 0xFF);
}
static void settle()
{
unsigned int i;
for (i = 0; i < 30; i++) {
}
}
static void csr_w(reg, v)
unsigned int reg, v;
{
*(unsigned short *)RAP = reg;
settle();
*(unsigned short *)RDP = v;
settle();
}
static unsigned int csr_r(reg)
unsigned int reg;
{
unsigned int v;
*(unsigned short *)RAP = reg;
settle();
v = *(unsigned short *)RDP;
settle();
return v;
}
/* ---- 5x7 text -------------------------------------------------------
* Glyphs are built at runtime: this toolchain never runs .cinit, so a
* statically initialised table would arrive as zeros (same reason
* harness/c-hello builds its font in code).
*/
static unsigned char glyph[36][7];
static unsigned char lab_csr0[5], lab_csr1[5], lab_tmd1[5], lab_rmd1[5];
static unsigned char lab_mcnt[5], lab_rest[5], lab_ok[3], lab_yes[4], lab_no[3];
static unsigned char lab_mac1[5], lab_mac2[5];
static unsigned int gi(ch)
unsigned int ch;
{
if (ch >= '0' && ch <= '9') {
return ch - '0';
}
return 10 + (ch - 'A');
}
static void fset(i, r0, r1, r2, r3, r4, r5, r6)
unsigned int i, r0, r1, r2, r3, r4, r5, r6;
{
glyph[i][0] = r0; glyph[i][1] = r1; glyph[i][2] = r2; glyph[i][3] = r3;
glyph[i][4] = r4; glyph[i][5] = r5; glyph[i][6] = r6;
}
static void build_font()
{
fset(0, 0x0E,0x11,0x13,0x15,0x19,0x11,0x0E); /* 0 */
fset(1, 0x04,0x0C,0x04,0x04,0x04,0x04,0x0E); /* 1 */
fset(2, 0x0E,0x11,0x01,0x02,0x04,0x08,0x1F); /* 2 */
fset(3, 0x1F,0x02,0x04,0x02,0x01,0x11,0x0E); /* 3 */
fset(4, 0x02,0x06,0x0A,0x12,0x1F,0x02,0x02); /* 4 */
fset(5, 0x1F,0x10,0x1E,0x01,0x01,0x11,0x0E); /* 5 */
fset(6, 0x06,0x08,0x10,0x1E,0x11,0x11,0x0E); /* 6 */
fset(7, 0x1F,0x01,0x02,0x04,0x08,0x08,0x08); /* 7 */
fset(8, 0x0E,0x11,0x11,0x0E,0x11,0x11,0x0E); /* 8 */
fset(9, 0x0E,0x11,0x11,0x0F,0x01,0x02,0x0C); /* 9 */
fset(gi('A'), 0x0E,0x11,0x11,0x1F,0x11,0x11,0x11);
fset(gi('B'), 0x1E,0x11,0x11,0x1E,0x11,0x11,0x1E);
fset(gi('C'), 0x0E,0x11,0x10,0x10,0x10,0x11,0x0E);
fset(gi('D'), 0x1E,0x11,0x11,0x11,0x11,0x11,0x1E);
fset(gi('E'), 0x1F,0x10,0x10,0x1E,0x10,0x10,0x1F);
fset(gi('F'), 0x1F,0x10,0x10,0x1E,0x10,0x10,0x10);
fset(gi('K'), 0x11,0x12,0x14,0x18,0x14,0x12,0x11);
fset(gi('M'), 0x11,0x1B,0x15,0x15,0x11,0x11,0x11);
fset(gi('N'), 0x11,0x19,0x19,0x15,0x13,0x13,0x11);
fset(gi('O'), 0x0E,0x11,0x11,0x11,0x11,0x11,0x0E);
fset(gi('R'), 0x1E,0x11,0x11,0x1E,0x14,0x12,0x11);
fset(gi('S'), 0x0F,0x10,0x10,0x0E,0x01,0x01,0x1E);
fset(gi('T'), 0x1F,0x04,0x04,0x04,0x04,0x04,0x04);
fset(gi('X'), 0x11,0x11,0x0A,0x04,0x0A,0x11,0x11);
fset(gi('Y'), 0x11,0x11,0x0A,0x04,0x04,0x04,0x04);
}
static void put4(a, c0, c1, c2, c3)
unsigned char *a;
unsigned int c0, c1, c2, c3;
{
a[0] = c0; a[1] = c1; a[2] = c2; a[3] = c3; a[4] = 0;
}
static void draw_glyph(x, y, ch)
unsigned int x, y, ch;
{
unsigned int r, c, row, idx;
idx = gi(ch);
for (r = 0; r < 7; r++) {
row = glyph[idx][r];
for (c = 0; c < 5; c++) {
if (row & (1 << (4 - c))) {
rect(x + c * 8, y + r * 3, 8, 3, 0xFF);
}
}
}
}
static void draw_text(x, y, s)
unsigned int x, y;
unsigned char *s;
{
while (*s) {
if (*s != ' ') {
draw_glyph(x, y, *s);
}
x = x + 48;
s = s + 1;
}
}
static void hex4(x, y, v)
unsigned int x, y, v;
{
unsigned int d, nib;
/* Wipe the field first. Only the glyph pixels were being written before,
* so 0005 drawn over 1234 left the tails of the old digits on screen. */
rect(x, y, 200, 24, 0x00);
for (d = 0; d < 4; d++) {
nib = (v >> ((3 - d) * 4)) & 0xF;
if (nib < 10) {
draw_glyph(x + d * 48, y, '0' + nib);
} else {
draw_glyph(x + d * 48, y, 'A' + nib - 10);
}
}
}
int main()
{
unsigned int i, n, idle, rxf, bytes, cmds, laststat, txslot, ncmd;
unsigned int buf, len, et, j, rmd1, chaindrop, txfull, errbits;
unsigned int jaddr, dojump;
cell(0x000, 1);
build_font();
put4(lab_csr0, 'R', 'X', 'F', ' ');
put4(lab_csr1, 'K', 'B', ' ', ' ');
put4(lab_tmd1, 'C', 'M', 'D', ' ');
put4(lab_rmd1, 'S', 'T', 'A', 'T');
put4(lab_mcnt, 'C', 'S', 'R', '0');
put4(lab_rest, 'R', 'E', 'S', 'T');
dot(0);
/* ---- chip: normal mode, our MAC, broadcast accepted ---- */
csr_w(0, CSR0_STOP);
w16(INITB + 0 * 16, 0x0000);
w16(INITB + 1 * 16, 0x0008);
w16(INITB + 2 * 16, 0x162b);
w16(INITB + 3 * 16, 0x5a4b);
w16(INITB + 4 * 16, 0); w16(INITB + 5 * 16, 0);
w16(INITB + 6 * 16, 0); w16(INITB + 7 * 16, 0);
w16(INITB + 8 * 16, (RXR >> 3) & 0xFFFF);
w16(INITB + 9 * 16, 4 << 13); /* 16 RX descriptors */
w16(INITB + 10 * 16, (TXR >> 3) & 0xFFFF);
w16(INITB + 11 * 16, 3 << 13); /* 8 TX descriptors */
for (i = 0; i < NRX; i++) {
buf = 0x4000 + i * RXBUFLEN;
w16(RXR + i * 64 + 0, buf & 0xFFFF);
w16(RXR + i * 64 + 16, RMD1_OWN | ((buf >> 16) & 0xFF));
w16(RXR + i * 64 + 32, (0x10000 - RXBUFLEN) & 0xFFFF);
w16(RXR + i * 64 + 48, 0);
}
for (i = 0; i < 8; i++) {
w16(TXR + i * 64 + 0, (TXBUF >> 3) & 0xFFFF);
w16(TXR + i * 64 + 16, ((TXBUF >> 3) >> 16) & 0xFF);
w16(TXR + i * 64 + 32, 0xF000);
w16(TXR + i * 64 + 48, 0);
}
csr_w(1, (INITB >> 3) & 0xFFFF);
csr_w(2, ((INITB >> 3) >> 16) & 0xFF);
csr_w(3, 0);
csr_w(0, 0x7F41);
for (idle = 0; idle < 20000; idle++) {
if (csr_r(0) & CSR0_IDON) {
break;
}
}
csr_w(0, 0x0042);
dot(1);
/* the ring is live from here: draw the panel only now, so frames
* that arrive during the (slow) VRAM fill are not missed */
rect(100, 650, 512, 256, 0x00);
rect(100, 650, 512, 4, 0xFF);
rect(100, 902, 512, 4, 0xFF);
rect(100, 650, 8, 256, 0xFF);
rect(608, 650, 8, 256, 0xFF);
rxf = 0; bytes = 0; cmds = 0; laststat = 0xEEEE; txslot = 0; ncmd = 0;
chaindrop = 0; txfull = 0; errbits = 0; jaddr = 0; dojump = 0;
/* ---- main loop: receive, count, and serve commands ---- */
for (idle = 0; ; idle++) {
for (i = 0; i < NRX; i++) {
rmd1 = r16(RXR + i * 64 + 16);
if (rmd1 & RMD1_OWN) {
continue;
}
buf = 0x4000 + i * RXBUFLEN;
len = r16(RXR + i * 64 + 48) & 0x0FFF;
/* Every reference driver (4.4BSD pmax if_le.c, NetBSD am7990.c,
* Linux 7990.c) requires STP *and* ENP on the same descriptor and
* drops a frame that spans descriptors instead of reassembling it.
* Testing ENP alone would count the tail of a jumbo frame as a
* frame and parse it from the middle of the buffer. */
if ((rmd1 & (RMD1_STP | RMD1_ENP)) != (RMD1_STP | RMD1_ENP)) {
chaindrop = chaindrop + 1;
REARM_RX(i, buf);
continue;
}
if (len < 60) {
len = 60;
}
rxf = rxf + 1;
/* the chip writes the 4-byte FCS into the buffer and includes it
* in RMD3; all three drivers subtract it (`mblength - 4`) */
if (len > 4) {
bytes = bytes + len - 4;
}
et = (rb((buf + 12) * 8) << 8) | rb((buf + 13) * 8);
ncmd = ncmd + 1;
/* command frame? ethertype 0x88B6, then 'K' 'S' <cmd> ... */
if (et == ETHCMD && rb((buf + 14) * 8) == 'K' && rb((buf + 15) * 8) == 'S') {
unsigned int cmd, addr, rlen, k, v;
cmd = rb((buf + 16) * 8);
addr = ((rb((buf + 17) * 8) << 24) | (rb((buf + 18) * 8) << 16) |
(rb((buf + 19) * 8) << 8) | rb((buf + 20) * 8));
rlen = (rb((buf + 21) * 8) << 8) | rb((buf + 22) * 8);
cmds = cmds + 1;
laststat = 0;
/* reply layout: [16]=cmd, [17..18]=status, [19..]=data */
for (j = 0; j < 6; j++) {
wb(TXBUF + j * 8, rb((buf + 6 + j) * 8)); /* dst = requester */
}
/* src = our own MAC. This used to copy the request's
* destination (a broadcast address) and a frame with a
* multicast source is dropped by the tap, so replies never
* arrived even though the command was handled. */
wb(TXBUF + 6 * 8, 0x08); wb(TXBUF + 7 * 8, 0x00);
wb(TXBUF + 8 * 8, 0x2B); wb(TXBUF + 9 * 8, 0x16);
wb(TXBUF + 10 * 8, 0x4B); wb(TXBUF + 11 * 8, 0x5A);
wb(TXBUF + 12 * 8, 0x88); wb(TXBUF + 13 * 8, 0xB6);
wb(TXBUF + 14 * 8, 'K'); wb(TXBUF + 15 * 8, 'S');
wb(TXBUF + 16 * 8, cmd);
len = 60;
if (cmd == 1) {
/* read memory: addr is a bit address, rlen bytes */
if (rlen > 64) {
rlen = 64;
laststat = 0xE001;
}
for (k = 0; k < 19 + rlen; k++) {
wb(TXBUF + (19 + k) * 8, 0);
}
for (k = 0; k < rlen; k++) {
v = rb(addr + k * 8);
wb(TXBUF + (19 + k) * 8, v);
}
if (19 + rlen > 60) {
len = 19 + rlen;
}
} else if (cmd == 2) {
/* statistics: rxf(4) bytes(4) cmds(2) chaindrop(2) txfull(2) */
wb(TXBUF + 19 * 8, (rxf >> 24) & 0xFF);
wb(TXBUF + 20 * 8, (rxf >> 16) & 0xFF);
wb(TXBUF + 21 * 8, (rxf >> 8) & 0xFF);
wb(TXBUF + 22 * 8, rxf & 0xFF);
wb(TXBUF + 23 * 8, (bytes >> 24) & 0xFF);
wb(TXBUF + 24 * 8, (bytes >> 16) & 0xFF);
wb(TXBUF + 25 * 8, (bytes >> 8) & 0xFF);
wb(TXBUF + 26 * 8, bytes & 0xFF);
wb(TXBUF + 27 * 8, (cmds >> 8) & 0xFF);
wb(TXBUF + 28 * 8, cmds & 0xFF);
wb(TXBUF + 29 * 8, (chaindrop >> 8) & 0xFF);
wb(TXBUF + 30 * 8, chaindrop & 0xFF);
wb(TXBUF + 31 * 8, (txfull >> 8) & 0xFF);
wb(TXBUF + 32 * 8, txfull & 0xFF);
wb(TXBUF + 33 * 8, (errbits >> 8) & 0xFF);
wb(TXBUF + 34 * 8, errbits & 0xFF);
} else if (cmd == 3) {
/* poke: the request carries the bytes from [23] on.
* `addr` is a BIT address, like every other address in
* this payload, so a byte address must be sent as
* byte_addr * 8. */
unsigned int wlen;
wlen = rlen;
if (wlen > 1024) { /* one frame holds this */
wlen = 1024;
laststat = 0xE003;
}
for (k = 0; k < wlen; k++) {
wb(addr + k * 8, rb((buf + 23 + k) * 8));
}
wb(TXBUF + 19 * 8, (wlen >> 8) & 0xFF);
wb(TXBUF + 20 * 8, wlen & 0xFF);
} else if (cmd == 4 || cmd == 5) {
/* jump (4) to an address, or reboot (5): jump to the ROM
* reset vector, which is the same entry the CPU takes at
* power-on. Its first instruction is DINT and it then
* initialises both DUARTs, so it does not depend on state
* this payload leaves behind. The reply is transmitted
* below, before control is transferred. */
if (cmd == 5) {
jaddr = *(unsigned int *)0xFFFFFFE0;
} else {
jaddr = addr;
}
dojump = 1;
wb(TXBUF + 19 * 8, (jaddr >> 24) & 0xFF);
wb(TXBUF + 20 * 8, (jaddr >> 16) & 0xFF);
wb(TXBUF + 21 * 8, (jaddr >> 8) & 0xFF);
wb(TXBUF + 22 * 8, jaddr & 0xFF);
} else {
laststat = 0xE002;
}
wb(TXBUF + 17 * 8, (laststat >> 8) & 0xFF);
wb(TXBUF + 18 * 8, laststat & 0xFF);
/* All the reference drivers check that the ring slot is free
* before reusing it (Linux stops the queue, NetBSD prints
* "missing buffer", 4.4BSD panics) -- we just skip. */
if (r16(TXR + txslot * 64 + 16) & TMD1_OWN) {
txfull = txfull + 1;
} else {
w16(TXR + txslot * 64 + 48, 0); /* TMD3 */
w16(TXR + txslot * 64 + 32, (0x10000 - len) & 0xFFFF);
w16(TXR + txslot * 64 + 16,
TMD1_OWN | TMD1_STP | TMD1_ENP | (((TXBUF >> 3) >> 16) & 0xFF));
/* 4.4BSD/NetBSD/Linux all kick with TDMD|INEA only; a
* repeated start (STRT) is not part of any of them. */
csr_w(0, 0x0040 | CSR0_TDMD);
for (j = 0; j < 20000; j++) {
if (!(r16(TXR + txslot * 64 + 16) & TMD1_OWN)) {
break;
}
}
}
txslot = (txslot + 1) & 7;
if (dojump) {
/* the reply has been transmitted (or waited on) above;
* from here this payload does not return */
void (*fp)();
fp = (void (*)()) jaddr;
(*fp)();
}
}
/* re-arm immediately (length and count first, ownership last, as
* NetBSD does: rmd1_bits = OWN; rmd2 = -LEBLEN|ONES; rmd3 = 0) */
REARM_RX(i, buf);
}
/* sticky chip error bits: ERR|BABL|CERR|MISS|MERR. MISS set means
* the chip had no descriptor to receive into (ring too small / loop
* too slow); clear means the frames never reached the chip. */
errbits = errbits | (csr_r(0) & 0xF800);
/* publish counters as we go */
cell(0x160, rxf); cell(0x180, bytes); cell(0x1A0, cmds); cell(0x200, laststat);
if ((idle & 0xFFF) == 0) {
draw_text(104, 654, lab_csr0); hex4(312, 654, rxf);
draw_text(104, 686, lab_csr1); hex4(312, 686, bytes >> 10);
draw_text(104, 718, lab_tmd1); hex4(312, 718, cmds);
draw_text(104, 750, lab_rmd1); hex4(312, 750, laststat);
draw_text(104, 782, lab_mcnt); hex4(312, 782, csr_r(0));
}
}
return 0;
}
View Git Blame Copy Permalink