Initial remote commit

2026-04-30 11:04:05 +00:00
commit b86e4f9a98
103 changed files with 262770 additions and 0 deletions
--- a/test/build_merged.py
+++ b/test/build_merged.py
@@ -0,0 +1,85 @@
+import struct
+
+CHUNK     = 128*512
+LV_START  = 5120000*512
+BSIZE     = 4096
+BPG       = 32768
+GDT_ENTRY = 64
+NUM_GROUPS = 35728
+
+def is_meta(virt_byte):
+    in_group  = virt_byte % (5*CHUNK)
+    return (in_group // CHUNK) == 4
+
+def raw_read(virt_offset, length):
+    result = bytearray(length)
+    pos = virt_offset
+    remaining = length
+    with open('/dev/md0','rb') as f:
+        while remaining > 0:
+            group     = pos // (5*CHUNK)
+            in_group  = pos % (5*CHUNK)
+            chunk_idx = in_group // CHUNK
+            intra     = in_group % CHUNK
+            seg_len   = min(CHUNK-intra, remaining)
+            dst_off   = pos - virt_offset
+            if chunk_idx != 4:
+                phys = LV_START + group*4*CHUNK + chunk_idx*CHUNK + intra
+                f.seek(phys)
+                data = f.read(seg_len)
+                result[dst_off:dst_off+len(data)] = data
+            pos += seg_len
+            remaining -= seg_len
+    return bytes(result)
+
+# Build merged GDT: for each group, use whichever of primary/backup
+# is NOT in a metadata chunk
+print('Building merged GDT...')
+primary_start = BSIZE                    # block 1
+backup_start  = (1*BPG + 1) * BSIZE     # group 1 backup
+
+# Read both GDTs in full
+primary_gdt = raw_read(primary_start, NUM_GROUPS * GDT_ENTRY)
+backup_gdt  = raw_read(backup_start,  NUM_GROUPS * GDT_ENTRY)
+
+merged = bytearray(NUM_GROUPS * GDT_ENTRY)
+primary_used = 0
+backup_used  = 0
+neither      = 0
+
+for g in range(NUM_GROUPS):
+    prim_byte   = primary_start + g * GDT_ENTRY
+    backup_byte = backup_start  + g * GDT_ENTRY
+    src_off     = g * GDT_ENTRY
+
+    if not is_meta(prim_byte):
+        # Primary is valid - use it
+        merged[src_off:src_off+GDT_ENTRY] = primary_gdt[src_off:src_off+GDT_ENTRY]
+        primary_used += 1
+    elif not is_meta(backup_byte):
+        # Primary is in metadata chunk - use backup
+        merged[src_off:src_off+GDT_ENTRY] = backup_gdt[src_off:src_off+GDT_ENTRY]
+        backup_used += 1
+    else:
+        # Both bad - shouldn't happen given our analysis
+        neither += 1
+
+print(f'From primary GDT: {primary_used}')
+print(f'From backup GDT:  {backup_used}')
+print(f'Neither (error):  {neither}')
+assert neither == 0, 'Unexpected gap in coverage!'
+
+# Verify merged GDT looks sane
+print()
+print('Sample entries:')
+for g in [0, 1, 100, 1000, 32699, 35000, 35727]:
+    e = merged[g*GDT_ENTRY:(g+1)*GDT_ENTRY]
+    bb = struct.unpack_from('<I',e,0)[0]
+    ib = struct.unpack_from('<I',e,4)[0]
+    it = struct.unpack_from('<I',e,8)[0]
+    cs = struct.unpack_from('<H',e,30)[0]
+    print(f'  Group {g:6d}: bb={bb:8d} ib={ib:8d} it={it:10d} csum=0x{cs:04x}')
+
+with open('/tmp/merged_gdt.bin','wb') as f:
+    f.write(merged)
+print(f'Saved /tmp/merged_gdt.bin ({len(merged)//1024}KB)')