Boot logo (init/bootlogo.c, init/logo_data.c, scripts/mklogo.py):
The logo appears in two forms because the framebuffer does not exist for the
first third of boot. An ASCII rendition goes to the text console and serial
line from the first moments; once the video driver is up at step [5/14] the
real bitmap takes over as a graphical splash with a progress bar tied to the
actual boot stages.
The asset is 4-bit palette indexed, so 160x160 pixels cost 12.5 KB instead of
100 KB, and carries a transparency mask so the mark composites onto the
gradient rather than stamping a flat rectangle over it. scripts/mklogo.py
regenerates init/logo_data.c from the source PNG.
Boot reaches the desktop in well under a second, so the splash is held for a
minimum duration and the bar sweeps to 100% during the hold; without that the
logo would flash past unseen. `splashtime=<ms>` tunes it and `nosplash`,
`nogui` or `text` skip it.
Bootloader (boot/stage2.asm):
stage2 staged the whole kernel in conventional RAM before copying it to 1 MB,
which capped the kernel at roughly 576 KB before the load ran into video
memory at 0xA0000. The logo pushed it over that line and the kernel stopped
booting. Each 32 KB chunk now goes into one fixed low buffer and is copied
straight to its final address, using unreal mode for the 32-bit reach. The
ceiling is now the image itself, 1.375 MB.
Console font (lib/font8x8.c):
fb_draw_char was a stub that ignored its character argument and drew a filled
rectangle, which is why the splash rendered its text as solid blocks. It now
renders real glyphs, and the table it uses is shared: the framebuffer console,
the canvas rasterizer and the desktop compositor had three divergent private
copies, two of which still carried the `// \` line-continuation defect.
printk console sink (kernel/printk.c):
printk output can be redirected to a callback, so a caller can run a subsystem
that reports via printk and capture what it printed. Serial and the dmesg ring
still see everything, which keeps a captured run debuggable.
Shell builtins (userland/lazybox/shell.c):
The builtin chain is extracted into shell_execute_builtin(), so the kernel TTY
and the desktop terminal accept the same vocabulary instead of the GUI seeing
only the applet table. Callers that cannot be suspended pass allow_blocking =
false to refuse the animating ones.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01L5yKJT4Wo2cV3rfPrwY5MP
Expands the kernel-and-TTY core with the primitives the higher layers have
been missing, plus an in-kernel harness that proves they work.
Data structures (lib/):
- rbtree.c: Linux-compatible red-black tree with parent pointers, full
insert/erase rebalancing, in-order iteration and an invariant validator.
- kfifo.c: power-of-two byte ring with free-running indices, so the wrap
path costs one mask instead of a branch per byte.
- hashtable.c: separately-chained table with FNV-1a hashing, string or
u64 keys, and rehash-on-growth at a 3/4 load factor.
Kernel subsystems:
- kernel/wait.c: wait queues and one-shot completion barriers, backed by a
static sleeper pool so a blocking path never re-enters the allocator.
- kernel/futex.c: 32-bucket futex hash with value re-check, requeue, and an
fmutex_t sleeping mutex built on the uncontended-fastpath protocol.
- kernel/rcu.c: tiny RCU with reader nesting, deferred callbacks, kfree_rcu
and rcu_assign_pointer/rcu_dereference publish barriers.
- mm/page_cache.c: write-back block page cache, 4 KB pages indexed by
(device, page), CLOCK second-chance eviction and dirty write-back.
- kernel/ktest.c: KUnit-style harness with 6 built-in suites, 21 cases and
735 assertions covering every subsystem above (all passing under QEMU).
LazyBox userland:
- coreutils.c: sort, uniq, cut, tr, rev, tac, nl, seq, diff, xxd, du,
factor, sum and truncate, reading through the VFS and handling the
zero-length synthetic nodes that procfs and sysfs expose.
- ktest, rcuinfo, futexinfo, waitinfo and pagecache diagnostics applets.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01L5yKJT4Wo2cV3rfPrwY5MP
- Add #include <lib/printf.h> in fs/vfs.c, include/lib/string.h, and include/kernel/printk.h
- Ensure snprintf is always declared during freestanding compilation
