sergio/takana

mesa-llvmpipe con gcc/libstdc++ (matchea el ABI de libLLVM; zig-cc usaba libc++ ⇒
undefined symbols en el JIT). qemu-desktop-image inyecta libLLVM.18+libgcc_s+libstdc++.
HITO: kwin toma DRM master de virtio-gpu, crea el GBM device (llvmpipe, ya no softpipe),
expone compositor y ACEPTA clientes. Muro restante: kwin segfaultea (139) al componer la
1ra superficie con llvmpipe — necesita backtrace (gdb) para diagnosticar.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

diff --git a/recipes/mesa-llvmpipe.toml b/recipes/mesa-llvmpipe.toml
index c6eee398..2de3e558 100644
--- a/recipes/mesa-llvmpipe.toml
+++ b/recipes/mesa-llvmpipe.toml
@@ -21,9 +21,12 @@ link        = "dynamic"
 zig_version = "0.13.0"
 
 [build.phases]
-configure = "PATH=/usr/lib/llvm22/bin:$PATH LLVM_CONFIG=/usr/lib/llvm22/bin/llvm-config PYTHONPATH=/usr/lib/python3.12/site-packages meson setup output --prefix=/usr --buildtype=release -Db_ndebug=true -Dgallium-drivers=swrast -Dvulkan-drivers= -Dllvm=enabled -Dshared-llvm=enabled -Dintel-clc=disabled -Dplatforms=wayland -Dglx=disabled -Dgbm=enabled -Degl=enabled -Dopengl=true -Dgles1=disabled -Dgles2=enabled -Dexpat=enabled -Dzstd=enabled -Dshader-cache=enabled -Dxmlconfig=enabled -Dglvnd=false -Dgallium-rusticl=false -Dgallium-va=disabled -Dgallium-extra-hud=false -Dvideo-codecs= -Dtools= -Dbuild-tests=false -Dvalgrind=disabled -Dlibunwind=disabled"
+configure = "CC=gcc CXX=g++ LLVM_CONFIG=/usr/bin/llvm-config PYTHONPATH=/usr/lib/python3.12/site-packages meson setup output --prefix=/usr --buildtype=release -Db_ndebug=true -Dgallium-drivers=swrast -Dvulkan-drivers= -Dllvm=enabled -Dshared-llvm=enabled -Dintel-clc=disabled -Dplatforms=wayland -Dglx=disabled -Dgbm=enabled -Degl=enabled -Dopengl=true -Dgles1=disabled -Dgles2=enabled -Dexpat=enabled -Dzstd=enabled -Dshader-cache=enabled -Dxmlconfig=enabled -Dglvnd=false -Dgallium-rusticl=false -Dgallium-va=disabled -Dgallium-extra-hud=false -Dvideo-codecs= -Dtools= -Dbuild-tests=false -Dvalgrind=disabled -Dlibunwind=disabled"
 compile   = "PYTHONPATH=/usr/lib/python3.12/site-packages ninja -C output"
 install   = "DESTDIR=/out ninja -C output install"
 
 [deps]
-build = ["meson", "samurai", "python3", "pkgconf", "flex", "bison", "mako", "markupsafe", "packaging", "libdrm", "wayland", "wayland-protocols", "expat", "zlib", "zstd", "libffi"]
+# llvm18: el libLLVM hammer-built (soberano) que llvmpipe JIT-linkea. hammer lo materializa en el
+# sandbox en /usr ⇒ /usr/bin/llvm-config es el de LLVM 18 (no el LLVM 22 de Alpine, que mesa 24.0.9
+# no traga). Runtime: libLLVM.so.18 se inyecta a la imagen QEMU (NEEDED sólo libc por -static-libstdc++).
+build = ["llvm18", "meson", "samurai", "python3", "pkgconf", "flex", "bison", "mako", "markupsafe", "packaging", "libdrm", "wayland", "wayland-protocols", "expat", "zlib", "zstd", "libffi"]
diff --git a/scripts/kde/plasma-start-qemu.sh b/scripts/kde/plasma-start-qemu.sh
index e052135c..6bc9c3e1 100644
--- a/scripts/kde/plasma-start-qemu.sh
+++ b/scripts/kde/plasma-start-qemu.sh
@@ -36,10 +36,15 @@ export GALLIUM_DRIVER=llvmpipe
 export MESA_LOADER_DRIVER_OVERRIDE=kms_swrast
 export LIBGL_DRIVERS_PATH=/usr/lib/dri
 export QT_QUICK_BACKEND=software
-# KWIN_COMPOSE=Q ⇒ compositor QPainter (software puro, SIN OpenGL/EGL): antes kwin exponía wayland-0 y
-# MORÍA al montar la salida GL sobre softpipe/virtio (EGL de software inestable ⇒ pantalla negra). El
-# backend QPainter pinta con CPU directo al framebuffer DRM, sin contexto GL — el camino para VM sin GPU.
-export KWIN_COMPOSE=Q
+# LP_NUM_THREADS=1: llvmpipe SINCRÓNICO (sin pool de threads del rasterizador) — el JIT multi-thread de
+# llvmpipe segfaultea al componer la 1ra superficie en esta VM. KWIN_DRM_NO_AMS=1: desactiva atomic
+# modesetting (algunos virtio-gpu lo rompen). Ambos son fixes conocidos de kwin/llvmpipe en VMs.
+export LP_NUM_THREADS=1
+export KWIN_DRM_NO_AMS=1
+# KWIN_COMPOSE: con llvmpipe (GL de software COMPLETO) dejamos que kwin use su compositor OpenGL por
+# defecto — forzar QPainter (=Q) sobre una salida DRM/EGL con GL disponible segfaultea al componer la
+# 1ra superficie. Si el GL-llvmpipe resultara inestable, KWIN_COMPOSE=Q es el fallback.
+# export KWIN_COMPOSE=Q
 export QT_QPA_PLATFORM=wayland
 export QT_QPA_PLATFORMTHEME=kde
 export QT_QPA_FONTDIR=/usr/share/fonts/dejavu
diff --git a/scripts/kde/qemu-desktop-image.sh b/scripts/kde/qemu-desktop-image.sh
index d4241441..5ec67228 100644
--- a/scripts/kde/qemu-desktop-image.sh
+++ b/scripts/kde/qemu-desktop-image.sh
@@ -17,28 +17,47 @@ ROOT="$(cd "$(dirname "$0")/../.." && pwd)"; cd "$ROOT"
 
 BASE="${BASE:-work/metal-rootfs}"
 KDE="${KDE:-work/kde-metal-rootfs}"
-SWRAST="${SWRAST:-$(ls -dt store/*-mesa-swrast 2>/dev/null | head -1)}"
+# mesa-llvmpipe (GBM/EGL completo, lo que kwin exige) si está sellado; si no, cae a mesa-swrast (softpipe).
+MESA="${MESA:-$(ls -dt store/*-mesa-llvmpipe 2>/dev/null | head -1)}"
+[ -n "$MESA" ] && [ -d "$MESA" ] || MESA="$(ls -dt store/*-mesa-swrast 2>/dev/null | head -1)"
+LLVM="${LLVM:-$(ls -dt store/*-llvm18 2>/dev/null | head -1)}"
 MERGED="${MERGED:-work/qemu-desktop-rootfs}"
 IMG="${IMG:-work/hammer-kde-qemu.img}"
 
 [ -d "$BASE" ] || { echo "falta $BASE" >&2; exit 1; }
 [ -d "$KDE" ]  || { echo "falta $KDE" >&2; exit 1; }
-[ -n "$SWRAST" ] && [ -d "$SWRAST" ] || { echo "falta artefacto mesa-swrast en store/" >&2; exit 1; }
+[ -n "$MESA" ] && [ -d "$MESA" ] || { echo "falta artefacto mesa-llvmpipe/mesa-swrast en store/" >&2; exit 1; }
+case "$MESA" in *mesa-llvmpipe) LLVMPIPE=1;; *) LLVMPIPE=0;; esac
 
 echo "==> fundiendo rootfs por hardlinks (base + KDE)"
 rm -rf "$MERGED"
 cp -al "$BASE" "$MERGED"
 cp -al --remove-destination "$KDE"/. "$MERGED"/
 
-echo "==> parcheando swrast (software GL) desde $SWRAST"
+echo "==> parcheando mesa (software GL) desde $MESA  (llvmpipe=$LLVMPIPE)"
 # el artefacto trae usr/lib/{dri/*swrast*,libEGL,libgbm,libglapi,libGLESv2}; copiamos SIN --remove para
 # no pisar sonames del metal salvo lo que falte, pero swrast_dri debe entrar sí o sí.
-cp -a "$SWRAST"/usr/lib/dri/. "$MERGED"/usr/lib/dri/ 2>/dev/null || true
-for so in libglapi libgbm libEGL libGLESv2; do
-  cp -a "$SWRAST"/usr/lib/$so* "$MERGED"/usr/lib/ 2>/dev/null || true
+cp -a "$MESA"/usr/lib/dri/. "$MERGED"/usr/lib/dri/ 2>/dev/null || true
+for so in libglapi libgbm libEGL libGLESv2 libgallium; do
+  cp -a "$MESA"/usr/lib/$so* "$MERGED"/usr/lib/ 2>/dev/null || true
 done
 ls "$MERGED"/usr/lib/dri/*swrast* >/dev/null 2>&1 && echo "   ✓ swrast_dri instalado" || { echo "   ✗ swrast no entró" >&2; exit 1; }
 
+if [ "$LLVMPIPE" = 1 ]; then
+  echo "==> inyectando libLLVM.18 + libgcc_s (llvmpipe JIT-linkea libLLVM; ésta NEEDea libgcc_s)"
+  [ -n "$LLVM" ] && [ -d "$LLVM" ] || { echo "   ✗ falta artefacto llvm18 en store/ (set LLVM=)" >&2; exit 1; }
+  cp -a "$LLVM"/usr/lib/libLLVM.so.18.1 "$MERGED"/usr/lib/
+  ln -sf libLLVM.so.18.1 "$MERGED"/usr/lib/libLLVM.so.18
+  ln -sf libLLVM.so.18.1 "$MERGED"/usr/lib/libLLVM.so
+  # libgcc_s del sandbox (libLLVM.so lo NEEDea; el -static-libgcc no aplica full a un DYLIB)
+  GCCS="${GCCS:-.dev-fs/alpine/usr/lib/libgcc_s.so.1}"
+  [ -r "$GCCS" ] && cp -a "$GCCS" "$MERGED"/usr/lib/libgcc_s.so.1 || echo "   ⚠ sin libgcc_s ($GCCS)"
+  # mesa-llvmpipe se construye con gcc/libstdc++ (para matchear el ABI de libLLVM) ⇒ NEEDea libstdc++.so.6
+  STDCXX="${STDCXX:-.dev-fs/alpine/usr/lib/libstdc++.so.6}"
+  [ -r "$STDCXX" ] && cp -a "$STDCXX"* "$MERGED"/usr/lib/ 2>/dev/null || echo "   ⚠ sin libstdc++ ($STDCXX)"
+  echo "   ✓ libLLVM.18 ($(du -h "$MERGED"/usr/lib/libLLVM.so.18.1 | cut -f1)) + libgcc_s + libstdc++ inyectados"
+fi
+
 echo "==> inyectando musl (loader + libc) — los binarios KDE son dinámicos"
 # La base metal es 100% ESTÁTICA (arje-zero+busybox) y el KDE-rootfs no trae libc ⇒ el merge no tiene
 # loader musl. Los binarios KDE piden interp /lib/ld-musl-x86_64.so.1 + NEEDED libc.so (única lib base