== size=32768 (pow2, control):
w=20480 r=20480
corrupted bytes: 0 / 20480  range [-1..-1]
PASS: no corruption
rc=0
== size=20480 (non-pow2):
w=20480 r=20480
corrupted bytes: 8192 / 20480  range [2048..10239]
FAIL: non-pow2 kern.pipe.size aliases FIFO slots and corrupts in-flight pipe data
rc=2
== size=24576 (non-pow2 #2):
w=20480 r=20480
corrupted bytes: 8192 / 20480  range [4096..12287]
FAIL: non-pow2 kern.pipe.size aliases FIFO slots and corrupts in-flight pipe data
rc=2
restored (kern.pipe.size=32768)
---
block-map confirmation (pipemap, 256B blocks, letters A..Z cycling):
expected letter seq: ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZAB
got      letter seq: ABCDEFGHOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZAB
(blocks 8..17 hold source blocks 40..49 - slot 2048..4607 overwritten by the
 write iteration that masked windex 10240&20479 -> 2048)