D03 STAGE2 OK
D03 PAYLOAD OK
D04 E820 OK
D04 A20 OK
D04 PM OK - BootInfo v1
EXCEPTION vector=3 error=0 eip=0x100fa6 cs=8 flags=402
EAX=11111111 EBX=44444444 ECX=22222222 EDX=33333333
ESI=66666666 EDI=77777777 EBP=55555555 PUSHAD_ESP=11cd44
DS=10 ES=10 FS=10 GS=10
EXCEPTION RETURN OK
D08 PIT divisor=11932 IRQ0 vector=32
TIMER ticks=10
TIMER ticks=20
TIMER OK - IRQ disabled for console regression
KERNEL_MAIN OK
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FMT ok Z -2147483648 4294967295 deadbeef 0x1234 %
ZERO 0 0 0 0x0 NULL (null)
unknown=%q trailing=%
abc
RB
CONSOLE OK
D10 physical pages 4 KiB cap=64 MiB
SYNTHETIC map overlap/round/high/overflow OK
E820 records=6 free=16067 kernel_end=0x11cdc0
allocator preserves IF=0 and IF=1 OK
unique/write/free OK; invalid/double free rejected
exhausted=16067 one-page reuse OK
all-page patterns OK recovered=16067
MEMORY OK
D11 paging 10/10/12 supervisor RW identity 64 MiB
PG+WP enabled CR3=0x11d000 same stack=0x11cd60
remap A -> B + INVLPG OK
PAGE FAULT CR2=0x40000000 error=0 EIP=0x102fa0
nonpresent read repaired; same EIP retry OK
PAGE FAULT CR2=0x40000000 error=3 EIP=0x102fa6
WP readonly write repaired; same EIP retry OK
PAGING OK retained tables=18 free=16049
D12 page-backed heap align=16 arenas=4
physical-page failure unchanged; recovery OK
sizes/patterns first-fit split/coalesce OK
overflow/invalid/double/tail/metadata reject OK
IF=0/1 preserved; exhausted=512 recovered=4 pages
HEAP OK retained paging tables=18
D13 TASKS A=128 B=128 switches=387 reaped=2
D13 stack used A=260 B=260 of 4096; locals/registers OK
TASKS OK pages recovered; IF=0/1 preserved
D14 PREEMPT A=742145 B=200000 switches=17
D14 seven-GPR/flags/DF probes=8; deferred ticks=3
D14 nested/IF0/CLI OK; stacks=324,324 reaped=2
PREEMPT OK pages recovered; returning to keyboard
D15 WAIT FIXED: real PIT producer, three event orders
D15 events produced=3 consumed=3 woken=0,1,1
D15 pending=1 lost=0 rescued=0 sleeps=8 idle=24
WAIT OK stacks=312,164 reaped=2 pages recovered
D16 ring3 round=0 private VA=40001000 bad=1
D16 fault=14 error=7 eip=4000005e survivor+=904249
D16 ring3 round=1 private VA=40001000 bad=2
D16 fault=13 error=0 eip=40000066 survivor+=901299
D16 ring3 round=2 private VA=40001000 bad=3
D16 fault=13 error=0 eip=4000006b survivor+=836757
USER OK ring3 CR3/TSS; rollback=7 reaped=6 pages=16049
D17 int80 write/yield and user-copy checks=4
D17 WRITE % NO-NUL
D17 READONLY OK
D17 CROSS-PAGE
D17 returns write=13 yield=0 unknown=ffffffda zero=0 long=ffffffea low=fffffff2 wrap=fffffff2 upper=fffffff2 missing=fffffff2 supervisor=fffffff2 ro=10 cross=f regs=1
D17 gate DPL #GP error=102 eip=40000077 survivor+=3844079
SYSCALL OK calls=12 writes=3 errors=7 irq_ticks=1 yield_delta=1799481 reaped=4
D18 ELF32 entry=40000080 image=4332 alloc=7 invalid=34 rollback=8
D18 ELF32 data/BSS/stack OK
ELF OK data/BSS/stack; code=RO data=RW rollback=8 reaped=1 pages=16049
D19 COUNT running
D19 BADPTR faulting
D19 COUNT exit=7
D19 REAP pid=2 status=7 by=wait pages=16033
D19 REAP pid=3 status=1000e by=wait pages=16041
D19 DEMO round OK
D19 COUNT running
D19 BADPTR faulting
D19 REAP pid=5 status=1000e by=wait pages=16033
D19 COUNT exit=7
D19 REAP pid=4 status=7 by=wait pages=16041
D19 DEMO round OK
D19 DEMO exit=9
D19 REAP pid=1 status=9 by=pid0 pages=16049
D19 COUNT running
D19 BADPTR faulting
D19 ORPHAN parent exits
D19 COUNT exit=7
D19 REAP pid=6 status=b by=pid0 pages=16033
D19 REAP pid=7 status=7 by=pid0 pages=16041
D19 REAP pid=8 status=1000e by=pid0 pages=16049
PROCESS OK mode=normal reaped=8 wait=4 blocks=2 faults=10 rollback=0 survivor+=3 pages=16049
D20 ATA primary master LBA28 sectors=16384 reads=3
D20 hashes mbr=98939bcd lba2047=c748f45 lba16383=d95e8545 range=3
BLOCK OK mode=0 result=0 followup=0 failed=0 ticks=0
D21 FAT mode=0 result=1479 part=2048+14336 clusters=14191 file=1479 read=1479 hash=f34dc752 steps=3 slices=3 bad=0 lba=2195
FAT OK mode=0
D22 FD begin
D22 CHILD shared offset +19
D19 REAP pid=10 status=13 by=wait pages=16042
D22 CHILD fault after shared +11
D19 REAP pid=11 status=1000e by=wait pages=16042
D19 REAP pid=12 status=0 by=wait pages=16035
D19 REAP pid=13 status=0 by=wait pages=16042
D22 readonly source accepted
D22 FD independent/shared offsets, EOF, errors and limits OK
D19 REAP pid=9 status=16 by=pid0 pages=16049
FD OK mode=0 reaped=5 exit-closes=14 rollback=0 blocks=0 pages=16049
# 
#    
# echo hello
hello
D19 REAP pid=15 status=0 by=wait pages=16043
# echo hello world
hello world
D19 REAP pid=16 status=0 by=wait pages=16043
# cat readme.txt
BUILD-AN-OS READ-ONLY FAT16 IMAGE

This file belongs to the teaching operating system built across the series.
The disk begins with a hand-written MBR and second-stage loader. The kernel is
loaded from fixed sectors so that the boot contract stays independent from the
file system introduced later.

Day 20 added a polling ATA PIO driver for the primary master. It identifies the
device, checks the LBA28 capacity, reads one 512-byte sector at a time, and
stops reusing the channel after a command timeout or device error.

Day 21 adds a read-only FAT16 layer above that block interface. The volume is
inside the first MBR partition. Its type is determined from the number of data
clusters, not from the FAT16 label. Directory entries use uppercase 8.3 names.

README.TXT is intentionally stored in a non-contiguous chain. Its first three
clusters are 2, 9, and 4. A correct reader must follow the FAT instead of adding
one to the previous cluster number. The directory file size, not the final
sector boundary, determines where the visible bytes end.

The tutorial keeps this volume read-only. It does not implement long file
names, subdirectories, allocation, truncation, crash recovery, or a buffer
cache. Corrupt BPB fields and corrupt cluster chains are rejected instead of
being converted into an apparently successful short read.

Later chapters will open this file through a descriptor, print it from the
user-mode shell, and send its bytes through a two-stage pipeline.
D19 REAP pid=17 status=0 by=wait pages=16043
# nosuch
shell: command not found
# echo recovered
recovered
D19 REAP pid=18 status=0 by=wait pages=16043
# argtest one two
ARGUMENT STACK OK
D19 REAP pid=19 status=0 by=wait pages=16043
# badmagic
shell: invalid executable
# echo afterbad
afterbad
D19 REAP pid=20 status=0 by=wait pages=16043
# fault
D19 REAP pid=21 status=1000e by=wait pages=16043
shell: child failed
# echo afterfault
afterfault
D19 REAP pid=22 status=0 by=wait pages=16043
# echo 1 2 3 4 5 6 7
1 2 3 4 5 6 7
D19 REAP pid=23 status=0 by=wait pages=16043
# echo 1 2 3 4 5 6 7 8
shell: too many arguments
# echo aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
D19 REAP pid=24 status=0 by=wait pages=16043
# echo bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
shell: argument too long
# echo x | wc
shell: syntax is not supported
# echo zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
shell: line too long
# echo final
final
D19 REAP pid=25 status=0 by=wait pages=16043
# exit
D19 REAP pid=14 status=0 by=pid0 pages=16049
SHELL OK prompts=20 pages=16049