Demand paging, the RTL8168H, links that come up late, and Ctrl+Alt+F1..F12

- Anonymous memory can be reserved without being backed: large mappings,
  MAP_NORESERVE and PROT_NONE are recorded and each page appears, zeroed,
  on first touch -- from trap() for the program, from uva2ka() for the
  kernel on its behalf. WebKit reserves 4 GB at start and touches a sliver;
  backing it all failed with ENOMEM and Epiphany aborted.
- r8169: the 8168G generation and later (the laptop's 8168H, XID 541) are
  taken from the firmware's out-of-band mode, get their PLL powered, the
  receive gate opened, and their PHY reached through the OCP window. The
  PHY's power-down bit is cleared; the old code kept it while restarting
  autonegotiation. Untested on the hardware so far.
- The network thread follows each device's link into lwIP. The link was
  read once at attach, 0.02 s into boot; real autonegotiation takes
  seconds, so on hardware the interface stayed down for good.
- Twelve terminals, switched with Ctrl+Alt+F1..F12 by default: the keys X
  uses, so the console and the desktop agree. AltGr+F-key is gone from
  the defaults (chvt -c altgr+F brings it back).
- SO_PASSCRED on Unix sockets, with SCM_CREDENTIALS delivered by recvmsg.
  WebKit sets it on its IPC sockets and aborted when refused.

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

docs/Website/download.html

@@ -243,9 +243,9 @@
       <span class="nv-steps__marker">4</span>
       <div class="nv-steps__body">
       <span class="nv-overline nv-text-tertiary">Step four</span>
-        <h3 class="nv-steps__title">Six terminals</h3>
+        <h3 class="nv-steps__title">Twelve terminals</h3>
         <p class="nv-steps__text">
-        <code class="nv-code">AltGr+F1</code>…<code class="nv-code">F6</code>
+        <code class="nv-code">Ctrl+Alt+F1</code>…<code class="nv-code">F12</code>
         switches between them — the one chord a Linux host does not take for
         itself — or <code class="nv-code">chvt N</code> from a shell.
         </p>

docs/Website/index.html

@@ -347,7 +347,7 @@
       </div>
       <div class="nv-card__body nv-text-secondary">
         Six of them, each with its own cell grid, scrollback and foreground
-        job — switched with <code class="nv-code">AltGr+F1</code>…<code class="nv-code">F6</code>,
+        job — switched with <code class="nv-code">Ctrl+Alt+F1</code>…<code class="nv-code">F12</code>,
         which is the one chord a Linux host does not take for itself. The console
         draws to whichever framebuffer is present, from the kernel's first line.
       </div>