Fix two bugs the Fedora move exposed

Neither is Fedora-specific. A different host and a freshly built
userland simply drove code that Windows never reached.

tools/mkfs.c did not compile at all. The DT_UNKNOWN/DT_DIR/DT_REG
fallbacks sat above <dirent.h>, so on glibc -- which spells them as
enumerators -- the #ifndef asked before the header was read, always
answered "missing", and then the header's own enum expanded to
`enum { 0 = 0, ... }`. Move the fallbacks below the include. The
include cannot move up instead: it has to follow the #undef that ends
the `#define dirent schfs_dirent` block.

getstackpcs() page-faulted. It dereferenced rbp[1] without validating
rbp, and the guard rejected 0xffffffff -- dead code on x86-64, already
caught by the KERNBASE test -- while the value that actually turns up
is all-ones, which is above KERNBASE. rbp[1] then wrapped to 0x7 and
took trap 14. `cp` panicked the kernel every time. Bound rbp from
above and require 8-byte alignment.

That second one masks other bugs: getcallerpcs() runs on every lock
acquisition and again from the trap handler, so a walker that can
fault replaces a real diagnosis with a bogus one.

Baseline on the Fedora laptop is now green: make ports, make,
make schfs-check including the round-trip that had never run, and
bootcheck at 27/27 plus 108 [ok] across the extended suites.

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

.claude/memory/schos-linux-machine.md

@@ -1,8 +1,10 @@
 ---
 name: schos-linux-machine
-description: The Fedora laptop, its project path and memory key, and the three things only it can test
-metadata:
-  node_type: project
+description: "The Fedora laptop, its project path and memory key, and the three things only it can test"
+metadata: 
+  node_type: memory
+  originSessionId: d4821aa9-2e49-40da-91e7-90ef9ed9997e
+  modified: 2026-08-09T17:26:30.874Z
 ---
 
 Nexoniarz works from **two machines** and moved the project to the second on
@@ -25,15 +27,23 @@ session that learned something.
 matters:
 
 1. **`make ports`** builds musl, toybox and mksh from source. Windows cannot do
-   it at all — the build skips ports and uses whatever is staged in `sysroot/`,
-   which is why `sysroot/bin/sh` still carries the pre-rename symbol
-   `__schunix_tp`.
+   it at all — the build skips ports and uses whatever is staged in `sysroot/`.
 2. **The SchFS round-trip test** needs symlinks and hard links, which Git Bash
-   cannot create, so it skips on Windows. **It has never actually run** — the
-   one part of SchFS with no coverage.
+   cannot create, so it skips on Windows.
 3. **KVM.** A Ryzen box has SVM, so QEMU runs at native speed. Deliberately not
    the Makefile default: the suite's timings were set under TCG.
 
+**All three ran for the first time on 2026-08-09, and the baseline is green:**
+`make ports` (the rebuilt `sysroot/bin/sh` no longer carries `__schunix_tp`),
+`make`, `make schfs-check` — round-trip included, collision pass and all —
+and `bootcheck.ps1` at 27/27, then 108 `[ok]` with
+`-Fb -Tty -Usb -Sock -Evdev -Ps`. Expect one "no prompt" on `wc -c` in the
+extended run; the check it feeds still passes, so it is pacing, not a fault.
+
+**The move exposed two latent bugs, both fixed the same day** — see
+[[schos-fedora-move-bugs]]. Neither was Fedora's fault; the host and the
+freshly built userland simply drove paths Windows never did.
+
 **PowerShell has no Fedora package**, and `tools/windows/bootcheck.ps1` is the
 test suite. pwsh runs it on Linux fine; it comes from Microsoft's repo or the
 GitHub tarball. Nothing else needs it.