X on the console: /dev/tty0, a palette, and startx that works

Xorg finds its VT through /dev/tty0, and without one ran on none: the
console went on drawing into the framebuffer over the X screen. tty0 is
the terminal on screen, as on Linux. FBIOPUTCMAP succeeds, as it does on
a true-colour Linux framebuffer, instead of 256 logged errors per start.

schos-base gives root a .xserverrc with -dumbSched, Xorg's switch for
input on the main loop: SchOS has no threads, and Xorg crashed in
pthread_join on its input thread when the first client left. It adds
the hostname to /etc/hosts, so xauth can resolve schos:0.

zsh loses PROMPT_SP: on a serial terminal narrower than the console its
padding wrapped and left a # above every prompt. bootcheck knows zsh's
prompt and matches without colour codes, so busybox's ls reads as text.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4

etc/zsh/zshrc

@@ -22,6 +22,12 @@ setopt EXTENDED_GLOB
 setopt INTERACTIVE_COMMENTS    # a # in an interactive line is a comment
 setopt NO_BEEP                 # SchOS has no audio, but it would also scroll
 unsetopt FLOW_CONTROL          # ^S/^Q are worth more as keys than as flow control
+# No PROMPT_SP. It marks output that did not end in a newline by printing a
+# `#` and then padding to $COLUMNS, trusting the terminal to wrap so the next
+# CR can erase it. The console is mirrored to the serial port, and a host
+# terminal narrower than the SchOS screen wraps the padding early: every
+# prompt came with a `#` line above it.
+unsetopt PROMPT_SP
 
 # ---------------------------------------------------------------------------
 # Keys

include/gfx/fb.h

@@ -19,6 +19,7 @@
 #define FBIOGET_VSCREENINFO 0x4600
 #define FBIOPUT_VSCREENINFO 0x4601
 #define FBIOGET_FSCREENINFO 0x4602
+#define FBIOPUTCMAP         0x4605
 #define FBIOBLANK           0x4611
 #define FBIOPAN_DISPLAY     0x4606
 

kernel/dev/fb.c

@@ -230,6 +230,13 @@ fb_ioctl(int request, addr_t arg)
   // blanking does too, as Linux's own drivers without the hook do.
   case FBIOBLANK:
     return 0;
+
+  // A palette, on a framebuffer that is always true-colour. Linux's drivers
+  // keep the values for the console's sixteen colours and succeed; refusing
+  // made Xorg's fbdev driver log an error for every entry it loads, 256 of
+  // them at each start.
+  case FBIOPUTCMAP:
+    return 0;
   }
 
   return -ENOTTY;

kernel/fs/devfs.c

@@ -83,6 +83,11 @@ static const struct devnode devnodes[] = {
      was one terminal. Minor 10 resolves through proc->ctty; see
      vt_for_minor() in kernel/core/console.c. */
   { "tty",     1, 10, D_ROOT },
+  /* The terminal on screen, as on Linux. Xorg opens it to find a free VT and
+     switch to it, and without one ran on no VT at all: the console went on
+     drawing into the framebuffer over the X screen. Any minor that is not a
+     numbered terminal or the controlling one resolves to vt_current(). */
+  { "tty0",    1, 0,  D_ROOT },
   { "tty1",    1, 11, D_ROOT },
   { "tty2",    1, 12, D_ROOT },
   { "tty3",    1, 13, D_ROOT },

tools/posix/mkaroot.sh

@@ -97,6 +97,18 @@ mkdir -p "$P/etc/profile.d"
 grep -v '^export \(PATH\|HOME\|TERM\)=' "$P/etc/profile" > "$P/etc/profile.d/schos.sh"
 rm -f "$P/etc/profile"
 
+# How startx starts the X server for root: Alpine's xserverrc, plus
+# -dumbSched. Xorg reads input on a thread of its own, SchOS has no threads
+# yet, and the server crashed on its way out the first time a client
+# disconnected, in pthread_join on a thread that was never made. -dumbSched is
+# Xorg's own switch for input on the main loop. The file is root's own rather
+# than /etc/X11/xinit/xserverrc, which belongs to the xinit package.
+mkdir -p "$P/root"
+cat > "$P/root/.xserverrc" <<'XEOF'
+#!/bin/sh
+exec /usr/bin/X -nolisten tcp -dumbSched "$@"
+XEOF
+
 # Mount points and runtime directories are alpine-baselayout's; an empty
 # directory here only duplicates it.
 for d in dev proc sys run tmp srv; do
@@ -110,6 +122,9 @@ sed -i 's|^\(root:[^:]*:0:0:[^:]*:[^:]*:\)/bin/sh$|\1/bin/zsh|' /etc/passwd
 for s in /bin/zsh /bin/mksh; do
     grep -qx "$s" /etc/shells 2>/dev/null || echo "$s" >> /etc/shells
 done
+# The machine's own name, which Alpine's hosts leaves out. Without it xauth
+# cannot resolve "schos:0", and startx says "bad display name" four times.
+grep -qw schos /etc/hosts || printf '127.0.1.1\tschos\n' >> /etc/hosts
 exit 0
 EOF
 cp "$PKG/post-install" "$PKG/post-upgrade"
@@ -157,7 +172,8 @@ ROOT_PI=$ROOT sh -c '
     sed -i "s|^\(root:[^:]*:0:0:[^:]*:[^:]*:\)/bin/sh$|\1/bin/zsh|" "$ROOT_PI/etc/passwd"
     for s in /bin/zsh /bin/mksh; do
         grep -qx "$s" "$ROOT_PI/etc/shells" 2>/dev/null || echo "$s" >> "$ROOT_PI/etc/shells"
-    done'
+    done
+    grep -qw schos "$ROOT_PI/etc/hosts" || printf "127.0.1.1\tschos\n" >> "$ROOT_PI/etc/hosts"'
 
 # The repository goes in too, so the installed system can reinstall and
 # upgrade schos-base, and Alpine's are listed for everything else.

tools/windows/bootcheck.ps1

@@ -495,8 +495,11 @@ try {
             Start-Sleep -Milliseconds 150
             $t = Read-Log
             if ($null -eq $t -or $t.Length -le $Since) { continue }
-            # A prompt at the very end, with nothing typed after it.
-            if ($t.Substring($Since) -match '(?s)#[ ]?$') { return $true }
+            # A prompt at the very end, with nothing typed after it: mksh's `#`,
+            # or zsh's `»`, which root's shell has been since the root became
+            # Alpine's. zsh follows it with erase-to-end-of-line and turns
+            # bracketed paste on, so both escapes may trail the prompt.
+            if ($t.Substring($Since) -match '(?s)(#|\u00bb)(\e\[[0-9;]*m)*[ ]?(\e\[K)?(\e\[\?2004h)?$') { return $true }
         }
         return $false
     }
@@ -629,6 +632,12 @@ if ($null -eq $text) { $text = '' }
 Write-Host "==> serial transcript ($($text.Length) bytes) -> $log" -ForegroundColor Cyan
 Write-Host $text
 
+# Matched without terminal escapes. busybox's ls, which is the Alpine root's,
+# colours what it lists -- `copy.txt` arrives as ESC[1;32mcopy.txt -- and zsh
+# wraps every prompt in them, so a pattern anchored at a line start found
+# nothing in output that was perfectly right. Shown raw above, matched clean.
+$text = $text -replace '\e\[[0-9;?]*[A-Za-z]', '' -replace '\e[()][0-9A-Za-z]', '' -replace '[\x0e\x0f]', ''
+
 $script:fail = $false
 function Expect($pattern, $what) {
     if ($script:text -match $pattern) {
@@ -697,7 +706,10 @@ Expect 'schfs: mounted'       'the kernel mounted SchFS as the root filesystem'
 Expect 'init: ready'          'init came up on a SchFS root'
 Expect 'label:\s*schos'     '/proc/schfs reports the volume label'
 Expect 'root_objectid:\s*16'  '/proc/schfs reports the root object id'
-Expect 'dir\s+bin'            'the root directory really contains bin/'
+# /proc/schfs lists the first 16 entries, in the tree's order, and on the
+# Alpine root bin/ is the seventeenth: any of the top-level directories proves
+# the same thing.
+Expect '(?m)^\s*dir\s+(bin|etc|usr)\s' 'the root directory really contains bin/, etc/ or usr/'
 # / is the mounted volume, so mounting that same device again must be
 # refused. Without this a kernel that had quietly fallen back to some other
 # root would still pass everything else here.