qemu-wasm: persistence, autoboot, console input, sensors, gabbro

- The 32 MB SPI flash is saved to OPFS when dirty (15 s cadence,
  strided FNV change detection) and restored on the next boot, so
  installed apps and settings survive reloads; PebbleKit JS sources
  are persisted alongside in localStorage. Factory reset wipes both.
- The page boots automatically on load (?noauto restores the button);
  switching boards reloads onto the chosen machine.
- gabbro (getafix_dvt) is a first-class board option with v4.35.0
  firmware in the site bundle.
- dbgserial (UART2) gains a browser input ring behind a wasm-console
  device property, giving the console panel a working prompt.
- Sensors & phone panel injects battery, compass, tap and time-format
  QemuProtocol frames over the existing serial bridge.

Verified in Chromium: autoboot, install -> OPFS save -> reload ->
restore (no re-fetch, JS registry intact), and the dbgserial prompt
answering 'help'.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pi1WErefJ7c6kXodajm25M
Signed-off-by: Eric Migicovsky <eric@repebble.com>

Author: Eric Migicovsky

tools/qemu-wasm/jit/overlay/hw/arm/pebble_generic.c

@@ -154,6 +154,10 @@ static void pbl_generic_init(MachineState *machine)
         if (i != 1) {
             qdev_prop_set_chr(dev, "chardev", serial_hd(i));
         }
+        if (i == 2) {
+            /* dbgserial: enable browser console input on wasm builds */
+            qdev_prop_set_bit(dev, "wasm-console", true);
+        }
         sysbus_realize_and_unref(sbd, &error_fatal);
         sysbus_mmio_map(sbd, 0, uart_base[i]);
         sysbus_connect_irq(sbd, 0, qdev_get_gpio_in(armv7m, uart_irq[i]));

tools/qemu-wasm/jit/overlay/hw/misc/pebble_simple_uart.c

@@ -17,12 +17,18 @@
 
 #include "qemu/osdep.h"
 #include "qemu/log.h"
+#include "qemu/timer.h"
 #include "hw/core/irq.h"
 #include "hw/core/sysbus.h"
+#include "hw/core/qdev-properties.h"
 #include "hw/core/qdev-properties-system.h"
 #include "hw/arm/pebble_simple_uart.h"
 #include "chardev/char-fe.h"
 
+#ifdef EMSCRIPTEN
+#include <emscripten/emscripten.h>
+#endif
+
 #define TYPE_PEBBLE_SIMPLE_UART "pebble-simple-uart"
 OBJECT_DECLARE_SIMPLE_TYPE(PblSimpleUart, PEBBLE_SIMPLE_UART)
 
@@ -68,8 +74,33 @@ struct PblSimpleUart {
     /* Optional write interceptor (for pebble_control) */
     PblUartWriteHandler write_handler;
     void *write_handler_opaque;
+
+    /* Browser console input (UART2 on the wasm build) */
+    bool wasm_console;
+#ifdef EMSCRIPTEN
+    QEMUTimer *wasm_poll_timer;
+#endif
 };
 
+#ifdef EMSCRIPTEN
+/* Ring for browser -> guest console bytes. The page appends at head
+ * (Atomics); an 8 ms virtual-clock poll feeds the RX FIFO. Enabled on
+ * the UART the machine marks wasm-console (the dbgserial prompt). */
+#define WASM_CON_RING 4096
+static uint8_t s_wasm_con_buf[WASM_CON_RING];
+static struct {
+    uint32_t buf, size;
+    uint32_t head, tail;
+} s_wasm_con_ctrl;
+
+EMSCRIPTEN_KEEPALIVE void *pebble_wasm_console_ctrl(void)
+{
+    s_wasm_con_ctrl.buf = (uint32_t)(uintptr_t)s_wasm_con_buf;
+    s_wasm_con_ctrl.size = WASM_CON_RING;
+    return &s_wasm_con_ctrl;
+}
+#endif
+
 static void pbl_uart_update_irq(PblSimpleUart *s)
 {
     bool level = false;
@@ -235,13 +266,46 @@ static void pbl_uart_receive(void *opaque, const uint8_t *buf, int size)
     }
 }
 
+#ifdef EMSCRIPTEN
+static void pbl_uart_wasm_poll(void *opaque)
+{
+    PblSimpleUart *s = opaque;
+    uint32_t head = qatomic_load_acquire(&s_wasm_con_ctrl.head);
+    uint32_t tail = s_wasm_con_ctrl.tail;
+
+    while (tail != head) {
+        int space = pbl_uart_can_receive(s);
+        if (space <= 0) {
+            break;
+        }
+        uint32_t off = tail % WASM_CON_RING;
+        uint32_t n = MIN(head - tail, WASM_CON_RING - off);
+        n = MIN(n, (uint32_t)space);
+        pbl_uart_receive(s, &s_wasm_con_buf[off], n);
+        tail += n;
+        qatomic_store_release(&s_wasm_con_ctrl.tail, tail);
+    }
+    timer_mod(s->wasm_poll_timer,
+              qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 8);
+}
+#endif
+
 static void pbl_uart_realize(DeviceState *dev, Error **errp)
 {
     PblSimpleUart *s = PEBBLE_SIMPLE_UART(dev);
 
     qemu_chr_fe_set_handlers(&s->chr, pbl_uart_can_receive,
                               pbl_uart_receive, NULL, NULL,
                               s, NULL, true);
+
+#ifdef EMSCRIPTEN
+    if (s->wasm_console) {
+        s->wasm_poll_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
+                                          pbl_uart_wasm_poll, s);
+        timer_mod(s->wasm_poll_timer,
+                  qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 8);
+    }
+#endif
 }
 
 static void pbl_uart_init(Object *obj)
@@ -269,6 +333,7 @@ static void pbl_uart_reset(DeviceState *dev)
 
 static const Property pbl_uart_properties[] = {
     DEFINE_PROP_CHR("chardev", PblSimpleUart, chr),
+    DEFINE_PROP_BOOL("wasm-console", PblSimpleUart, wasm_console, false),
 };
 
 static void pbl_uart_class_init(ObjectClass *klass, const void *data)

tools/qemu-wasm/site-dist/apply.sh

@@ -17,6 +17,9 @@ gunzip -c "$src/qemu-system-arm.js.gz" > "$dst/qemu-system-arm.js"
 gunzip -c "$src/qemu-system-arm.wasm.gz" > "$dst/qemu-system-arm.wasm"
 gunzip -c "$src/qemu_micro_flash.bin.gz" > "$dst/firmware/emery/qemu_micro_flash.bin"
 gunzip -c "$src/qemu_spi_flash.bin.gz" > "$dst/firmware/emery/qemu_spi_flash.bin"
+mkdir -p "$dst/firmware/gabbro"
+gunzip -c "$src/qemu_micro_flash_gabbro.bin.gz" > "$dst/firmware/gabbro/qemu_micro_flash.bin"
+gunzip -c "$src/qemu_spi_flash_gabbro.bin.gz" > "$dst/firmware/gabbro/qemu_spi_flash.bin"
 
 echo "Applied. New site files:"
 (cd "$dst" && ls -la index.html qemu-system-arm.js qemu-system-arm.wasm \