76 lines
2.3 KiB
Markdown
76 lines
2.3 KiB
Markdown
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# FreeBSD installer-derived live USB: XKB, `/var`, and tmpfs overlays
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Use this note when a custom FreeBSD live/operator USB boots but the graphical desktop fails with Xorg/XKB errors or a black screen.
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## Symptom pattern
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Common visible errors:
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```text
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Couldn't change directory to "/usr/local/share/X11/xkb"
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Can't find file "xfree86" for keycodes include
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XKB: Failed to compile keymap
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Keyboard initialization failed. This could be a missing or incorrect setup of xkeyboard-config.
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Fatal server error: Failed to activate virtual core keyboard: 2
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```
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The file may still exist when checked manually:
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```sh
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ls -l /usr/local/share/X11/xkb/keycodes/xfree86
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```
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If it exists, do not stop at “missing xkeyboard-config”. Check the live filesystem layout.
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## Why it happens
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Stock FreeBSD installer memsticks are installer-oriented and can mount small tmpfs-style overlays on `/tmp` and `/var`. In a desktop/operator USB that has a writable UFS root, those overlays can be harmful:
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- `/var/lib/xkb` may be hidden or missing at runtime.
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- Xorg/rootless XKB cache generation may fail.
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- `/var` may be too small for desktop services.
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- The resulting errors can misleadingly point at `/usr/local/share/X11/xkb`.
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## Runtime proof commands
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Run these on the failing USB:
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```sh
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mount | egrep ' on / | on /tmp | on /var '
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cat /etc/fstab
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egrep 'root_rw_mount|tmpmfs|varmfs' /etc/rc.conf /etc/rc.conf.local 2>/dev/null
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touch /root/probe 2>&1
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touch /tmp/probe 2>&1
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touch /var/tmp/probe 2>&1
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ls -ld /var/lib/xkb /usr/local/share/X11/xkb /usr/local/share/X11/xkb/keycodes
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```
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Interpretation:
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- Desired desktop/operator USB: `/` is writable UFS, and `/tmp` + `/var` are not separate tiny tmpfs mounts.
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- Suspicious: `tmpfs on /var` or tiny `/var`, especially with XKB cache/runtime failures.
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## Build-time fix pattern
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For writable live/operator USBs, build scripts should write or validate:
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```sh
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/dev/ufs/FreeBSD_Install / ufs rw,noatime 1 1
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root_rw_mount="YES"
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tmpmfs="NO"
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varmfs="NO"
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```
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Also add static checks to fail the build if these entries are absent.
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## Avoid false leads
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A user shell profile such as `~/.profile`/`~/.xprofile` that only sets `PATH`, best-effort loads `mac_do`, or launches a bootstrap page is unlikely to explain:
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- read-only root
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- hidden `/var/lib/xkb`
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- missing XKB runtime/cache paths
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- black screen before desktop startup
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Check mounts and rc.conf first.
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