starkernel: item 3.2 -- Stadium boot-time allocation

Punch list §25 item 3.2 complete.

stadium_boot_init() (src/starkernel/vm/stadium.c) sizes the global
cell array at boot from a real memory-budget query rather than a
hardcoded count: pmm_get_stats().free_bytes at the point of
allocation, times the new STADIUM_MEMORY_PERCENT Kconfig symbol
(default 1%), rounded down to whole 64-byte cells. Matches §17.6's
position (b) literally. Also allocates the header/continuation
discriminator bitmap item 3.1 declared but did not allocate. Both are
kmalloc'd and explicitly zero-filled (kmalloc does not zero).

Called from kernel_main.c immediately before sk_vm_bootstrap_parity(),
i.e. before any VM exists (§6). Failure is soft -- logs and continues,
does not halt boot -- matching the existing precedent one line below
it (VM bootstrap parity failure does the same).

Added a "Stadium: N cells (M KB)" boot console line at the allocation
site so the acceptance logs are evidence the array was actually
allocated, not just that the kernel still boots -- the same blind spot
item 3.1's uncompiled-header gap exposed.

Verified: three-architecture boot (amd64, aarch64, riscv64), all
reaching ok> with identical dict_hash=0x3d4e1daf289da94f matching the
item-3.1 baseline, and the Stadium boot line confirmed present in all
three serial logs (amd64: 74234 cells/4639 KB, aarch64: 161329
cells/10083 KB, riscv64: 76122 cells/4757 KB).

Not built here, reported per §25.0 rule 3: per-VM free lists (§22.3)
-- granted when Hera assigns quota, not this item's scope.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

FABRIC.md

@@ -2705,8 +2705,40 @@ document and committing that amendment as its own item.*
   > with identical `dict_hash=0x3d4e1daf289da94f` -- amd64 (`logs/20260804-151032`), aarch64
   > (`logs/20260804-151115`), riscv64 (`logs/20260804-151222`).
 
-- [ ] **3.2 — Boot-time allocation.** One global cell array, sized from the memory budget,
+- [x] **3.2 — Boot-time allocation.** One global cell array, sized from the memory budget,
   before any VM exists. *Refs:* §6, §17.6, §22.3.
+
+  > **DONE 2026-08-04.** Sizing ruled by Captain Bob among three options (flat Kconfig
+  > constant / runtime PMM-derived / `STADIUM_MAX_VM_COUNT × STADIUM_CELLS_PER_VM`):
+  > **runtime PMM-derived**, matching §17.6 position (b) literally rather than position (a),
+  > the "arbitrary bound" that section argues against. New `STADIUM_MEMORY_PERCENT` Kconfig
+  > symbol (default 1%, ruled by Captain Bob) — `stadium_boot_init()` in `stadium.c` reads
+  > `pmm_get_stats().free_bytes` at the point of allocation, takes that percent, rounds down
+  > to whole `STADIUM_CELL_BYTES` cells. Both the cell array and the discriminator bitmap
+  > item 3.1 declared but did not allocate are `kmalloc`'d here and explicitly zero-filled
+  > (`kmalloc` does not zero — checked `kmalloc.c`, no `memset`). Called from
+  > `kernel_main.c`, immediately before `sk_vm_bootstrap_parity()` — before any VM exists,
+  > per §6. Failure is soft (logs, returns -1, does not halt boot): nothing downstream
+  > consumes the Stadium yet, matching the existing precedent one line below it
+  > (`sk_vm_bootstrap_parity()`'s own failure path also just logs and continues).
+  >
+  > **Made observable, by agreement before writing code** (same blind spot the item-3.1
+  > uncompiled-header gap exposed): a `Stadium: N cells (M KB)` console line at the
+  > allocation site, so the three-arch boot's serial logs are evidence the array was
+  > actually allocated at the size intended, not just that the kernel still boots.
+  >
+  > **Regression: clean, and the boot line confirmed present on all three.** All three
+  > architectures boot to `ok>` with identical `dict_hash=0x3d4e1daf289da94f`, matching the
+  > item-3.1 baseline. Observed sizes (1% of free memory at the allocation point, this
+  > session's QEMU configuration): amd64 74234 cells (4639 KB, `logs/20260804-164332`),
+  > aarch64 161329 cells (10083 KB, `logs/20260804-164432`), riscv64 76122 cells (4757 KB,
+  > `logs/20260804-164537`). Reported, not evaluated against §23.3's ~4096-cells-per-VM
+  > illustrative figure — that figure is itself labeled a proposal to validate, not a target
+  > this item is scored against.
+  >
+  > **Explicitly not built here, reported per §25.0 rule 3:** per-VM free lists (§22.3, "each
+  > VM holds its own free-list head index into the global array") — those get granted when
+  > Hera assigns a VM its quota, which is not this item's scope.
 - [ ] **3.3 — Behaviour enumeration and dispatch.** Closed tag set fixed at build time.
   Enumerate behaviours, never patron kinds. *Refs:* §13, §18.3.
 - [ ] **3.4 — Density ranking.** Heat ÷ mass, read not computed. *Refs:* §19.2, §19.3.

Kconfig.kernel

@@ -79,6 +79,20 @@ config STADIUM_CAPACITY_TICK
 	  (FABRIC.md §22.4). No consumer yet -- capacity arbitration
 	  itself is not yet on the punch list.
 
+config STADIUM_MEMORY_PERCENT
+	int "Percent of free physical memory the Stadium claims at boot (STADIUM_MEMORY_PERCENT)"
+	default 1
+	help
+	  The Stadium's global cell array is sized at boot from
+	  pmm_get_stats().free_bytes, taken at the point of allocation
+	  (FABRIC.md item 3.2, §17.6 position (b): "sized at boot from the
+	  memory budget", not a hardcoded cell count). This is the fraction
+	  of that free-byte figure the array claims, rounded down to whole
+	  64-byte cells. Default of 1% is conservative -- comfortably clears
+	  the ~4096-cells-per-VM illustrative figure in FABRIC.md §23.3
+	  against a QEMU -m 1024 test config while leaving the kernel heap
+	  and everything else nearly all of physical memory.
+
 endif # STARFORTH_VARIANT_KERNEL
 
 endmenu

Makefile.starkernel

@@ -280,6 +280,7 @@ $(eval $(call kconfig_int,HEARTBEAT_INFERENCE_FREQUENCY,1000))
 $(eval $(call kconfig_int,STADIUM_MAX_VM_COUNT,4))
 $(eval $(call kconfig_int,STADIUM_CONTAINS_DEPTH_MAX,5))
 $(eval $(call kconfig_int,STADIUM_CAPACITY_TICK,1000))
+$(eval $(call kconfig_int,STADIUM_MEMORY_PERCENT,1))
 $(eval $(call kconfig_int,SSM_ENTROPY_HIGH_THRESHOLD,0.75))
 $(eval $(call kconfig_int,SSM_CV_HIGH_THRESHOLD,0.15))
 $(eval $(call kconfig_int,SSM_TEMPORAL_DECAY_THRESHOLD,0.5))
@@ -325,6 +326,7 @@ VM_FEATURE_FLAG_VARS := \
     HEARTBEAT_SLOPE_VALIDATION_FREQUENCY SK_PARITY_DEBUG \
     EMERGENCY_CONSOLE_ENABLED STADIUM_MAX_VM_COUNT \
     STADIUM_CONTAINS_DEPTH_MAX STADIUM_CAPACITY_TICK \
+    STADIUM_MEMORY_PERCENT \
     SSM_ENTROPY_HIGH_THRESHOLD SSM_CV_HIGH_THRESHOLD \
     SSM_TEMPORAL_DECAY_THRESHOLD SSM_TEMPORAL_DECAY_LOW_THRESHOLD \
     SSM_HYSTERESIS_TICKS \

capsules/BLOCK_MAP.md

@@ -1,5 +1,5 @@
 # Capsule Block Manifest — Auto-generated
-<!-- Generated by mkcapsule --manifest  2026-08-04T19:12:08Z -->
+<!-- Generated by mkcapsule --manifest  2026-08-04T20:45:23Z -->
 <!-- DO NOT EDIT — re-run mkcapsule --manifest to refresh.  -->
 <!-- Hand-written justifications and immutability notes live  -->
 <!-- in MANIFEST.md alongside this auto-generated index.      -->

experiments/bare_metal/runs/doe-aarch64-20260804-164432.csv

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experiments/bare_metal/runs/doe-amd64-20260804-164332.csv

@@ -0,0 +1,59 @@
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experiments/bare_metal/runs/doe-riscv64-20260804-164537.csv

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include/starforth_config.h

@@ -73,6 +73,7 @@
 #define STARFORTH_CONFIG_STADIUM_MAX_VM_COUNT_DEFAULT 4
 #define STARFORTH_CONFIG_STADIUM_CONTAINS_DEPTH_MAX_DEFAULT 5
 #define STARFORTH_CONFIG_STADIUM_CAPACITY_TICK_DEFAULT 1000
+#define STARFORTH_CONFIG_STADIUM_MEMORY_PERCENT_DEFAULT 1
 #define STARFORTH_CONFIG_HEARTBEAT_CHECK_FREQUENCY_DEFAULT 256
 #define STARFORTH_CONFIG_HEARTBEAT_WINDOW_TUNING_FREQUENCY_DEFAULT 1000
 #define STARFORTH_CONFIG_HEARTBEAT_SLOPE_VALIDATION_FREQUENCY_DEFAULT 5000
@@ -170,6 +171,10 @@
 #define STADIUM_CAPACITY_TICK STARFORTH_CONFIG_STADIUM_CAPACITY_TICK_DEFAULT
 #endif
 
+#ifndef STADIUM_MEMORY_PERCENT
+#define STADIUM_MEMORY_PERCENT STARFORTH_CONFIG_STADIUM_MEMORY_PERCENT_DEFAULT
+#endif
+
 #ifndef HEARTBEAT_CHECK_FREQUENCY
 #define HEARTBEAT_CHECK_FREQUENCY STARFORTH_CONFIG_HEARTBEAT_CHECK_FREQUENCY_DEFAULT
 #endif

include/starkernel/vm/stadium.h

@@ -34,8 +34,9 @@
 
 #ifdef __STARKERNEL__
 
+#include <stddef.h>
 #include <stdint.h>
-#include "starforth_config.h" /* STADIUM_CONTAINS_DEPTH_MAX, STADIUM_CAPACITY_TICK */
+#include "starforth_config.h" /* STADIUM_CONTAINS_DEPTH_MAX, STADIUM_CAPACITY_TICK, STADIUM_MEMORY_PERCENT */
 
 #define STADIUM_CELL_BYTES 64
 
@@ -103,6 +104,40 @@ typedef char stadium_cell_size_check[(sizeof(StadiumCell) == STADIUM_CELL_BYTES)
 typedef char stadium_contains_depth_configured_check[(STADIUM_CONTAINS_DEPTH_MAX > 0) ? 1 : -1];
 typedef char stadium_capacity_tick_configured_check[(STADIUM_CAPACITY_TICK > 0) ? 1 : -1];
 
+/*
+ * stadium_boot_init - Boot-time allocation (FABRIC.md item 3.2, §17.6 position
+ * (b)). Sizes the global cell array from the memory budget actually observed
+ * at boot -- STADIUM_MEMORY_PERCENT of pmm_get_stats().free_bytes at the
+ * point of the call, rounded down to whole STADIUM_CELL_BYTES cells -- rather
+ * than a hardcoded count. Also allocates the header/continuation discriminator
+ * bitmap item 3.1 declared but did not allocate: one bit per cell, bit set
+ * means the cell at that index is a patron header, clear means continuation
+ * or not yet in use. Both are kmalloc'd (freestanding kernel, no separate
+ * PMM-backed region needed for this) and explicitly zero-filled, since
+ * kmalloc does not zero.
+ *
+ * Must be called after M6 (kmalloc_init) and before any VM is born (§6). Does
+ * not halt boot on failure -- nothing downstream consumes the Stadium yet.
+ *
+ * @return 0 on success, -1 if kmalloc failed for either allocation.
+ */
+int stadium_boot_init(void);
+
+/* stadium_is_initialized - Whether stadium_boot_init() has succeeded. */
+int stadium_is_initialized(void);
+
+/* stadium_cell_count - Number of cells in the array, 0 if not initialized. */
+size_t stadium_cell_count(void);
+
+/* stadium_cells - Pointer to the cell array, NULL if not initialized. */
+StadiumCell *stadium_cells(void);
+
+/*
+ * stadium_header_bitmap - Pointer to the discriminator bitmap declared in
+ * item 3.1, NULL if not initialized. ceil(stadium_cell_count() / 8) bytes.
+ */
+uint8_t *stadium_header_bitmap(void);
+
 #endif /* __STARKERNEL__ */
 
 #endif /* STARKERNEL_VM_STADIUM_H */

src/starkernel/kernel_main.c

@@ -52,6 +52,7 @@ EFI_RUNTIME_SERVICES *g_sk_runtime_services = NULL;
 #ifdef STARFORTH_ENABLE_VM
 #include "starkernel/vm/bootstrap/sk_vm_bootstrap.h"
 #include "starkernel/vm/parity.h"
+#include "starkernel/vm/stadium.h"
 #include "starkernel/capsule_generated.h"
 #include "starkernel/capsule_loader.h"
 #include "starkernel/capsule_birth.h"  /* capsule_birth_mama, capsule_find_mama_init */
@@ -478,6 +479,11 @@ static void kernel_main_deep(BootInfo *boot_info) {
     console_println("Boot successful!\n");
 
 #ifdef STARFORTH_ENABLE_VM
+    /* Stadium: boot-time allocation (FABRIC.md item 3.2), before any VM
+     * exists (§6). Soft failure -- nothing downstream consumes the Stadium
+     * yet, so a failed allocation logs and boot continues. */
+    (void)stadium_boot_init();
+
     /* M7: VM Bootstrap and Parity Validation */
     console_println("VM: bootstrap parity...");
     ParityPacket parity_pkt;

src/starkernel/vm/stadium.c

@@ -22,12 +22,102 @@
  */
 
 /**
- * stadium.c - Translation unit for the Stadium cell definitions (item 3.1).
+ * stadium.c - The Stadium cell definitions (item 3.1) and boot-time
+ * allocation (item 3.2).
  *
- * Exists so stadium.h's compile-time size assertions are actually compiled
+ * Also the translation unit that makes stadium.h's compile-time assertions
- * on all three architectures, not merely included by something that never
+ * actually get compiled on all three architectures, not merely included by
- * builds. No behavior yet -- item 3.2 onward adds the array, dispatch, and
+ * something that never builds.
- * ranking.
  */
 
-#include "starkernel/vm/stadium.h"
+#include "starkernel/vm/stadium.h"
+
+#ifdef __STARKERNEL__
+
+#include "starkernel/kmalloc.h"
+#include "starkernel/pmm.h"
+#include "starkernel/console.h"
+
+static StadiumCell *stadium_cell_array   = (StadiumCell *)0;
+static uint8_t      *stadium_bitmap       = (uint8_t *)0;
+static size_t         stadium_ncells      = 0;
+static int             stadium_initialized = 0;
+
+/* Freestanding: no libc printf. Prints an unsigned decimal, no leading zeros. */
+static void console_put_u64(uint64_t v) {
+    char buf[21];
+    int  i = 20;
+    buf[20] = '\0';
+    if (v == 0) {
+        console_puts("0");
+        return;
+    }
+    while (v > 0 && i > 0) {
+        buf[--i] = (char)('0' + (v % 10));
+        v /= 10;
+    }
+    console_puts(&buf[i]);
+}
+
+int stadium_boot_init(void) {
+    pmm_stats_t pmm = pmm_get_stats();
+    uint64_t budget_bytes = (pmm.free_bytes * (uint64_t)STADIUM_MEMORY_PERCENT) / 100u;
+    size_t   ncells       = (size_t)(budget_bytes / STADIUM_CELL_BYTES);
+    size_t   bitmap_bytes = (ncells + 7u) / 8u;
+
+    if (ncells == 0) {
+        console_println("Stadium: boot-time allocation skipped (0 cells from memory budget)");
+        return -1;
+    }
+
+    StadiumCell *cells  = (StadiumCell *)kmalloc(ncells * STADIUM_CELL_BYTES);
+    uint8_t      *bitmap = (uint8_t *)kmalloc(bitmap_bytes);
+    if (!cells || !bitmap) {
+        console_println("Stadium: kmalloc failed for boot-time allocation");
+        if (cells)  kfree(cells);
+        if (bitmap) kfree(bitmap);
+        return -1;
+    }
+
+    {
+        uint8_t *raw = (uint8_t *)cells;
+        size_t   n   = ncells * STADIUM_CELL_BYTES;
+        size_t   i;
+        for (i = 0; i < n; i++) raw[i] = 0;
+    }
+    {
+        size_t i;
+        for (i = 0; i < bitmap_bytes; i++) bitmap[i] = 0;
+    }
+
+    stadium_cell_array  = cells;
+    stadium_bitmap      = bitmap;
+    stadium_ncells      = ncells;
+    stadium_initialized = 1;
+
+    console_puts("Stadium: ");
+    console_put_u64((uint64_t)ncells);
+    console_puts(" cells (");
+    console_put_u64((uint64_t)(ncells * STADIUM_CELL_BYTES) / 1024u);
+    console_println(" KB)");
+
+    return 0;
+}
+
+int stadium_is_initialized(void) {
+    return stadium_initialized;
+}
+
+size_t stadium_cell_count(void) {
+    return stadium_ncells;
+}
+
+StadiumCell *stadium_cells(void) {
+    return stadium_cell_array;
+}
+
+uint8_t *stadium_header_bitmap(void) {
+    return stadium_bitmap;
+}
+
+#endif /* __STARKERNEL__ */