wall-2 session-77: vkCreateDevice PASSES - r682 0x7E event validated live (registered slot 13, EVPOST rc=0) and the completion word found/driven: the main-thread wait reads a u32 at +0x80 of a 16 KB rw-s /dev/nvidiactl notification mapping (should-wait = word != 1); a host write of 1 via the guest RAM file (PA from pagemap, file offset PA-0x80000000 above 4G) flips the wait and vkCreateDevice returns success (VKDEVICE ok family=0) - reproduced 3x (r683 manual, r684 nudger, r684d probe+single-word). Tools: t79.py (wait-chain resolver), guest_words.sh, nudge.sh; README-session77.md records the recipe, the residual guest event-dispatch gap (records consumed, notification word not written), and the -4/gdb-attach cautions.

1 files changed, 17 insertions, 0 deletions

diff --git a/tools/guest-diag/wall2/guest_words.sh b/tools/guest-diag/wall2/guest_words.sh
new file mode 100755
index 0000000..6ac200c
--- /dev/null
+++ b/tools/guest-diag/wall2/guest_words.sh
@@ -0,0 +1,17 @@
+#!/bin/bash
+# guest_words.sh - print "VA PA" for the +0x80 word of every 16 KB rw-s
+# /dev/nvidiactl mapping of the vk_frame client (pagemap PFN -> PA).
+PID=$(pgrep -x vk_frame | head -1)
+[ -z "$PID" ] && exit 0
+sudo grep -E 'rw-s' /proc/$PID/maps | grep nvidiactl | while read -r line; do
+  RNG=$(echo "$line" | awk '{print $1}')
+  LO=${RNG%-*}; HI=${RNG#*-}
+  SZ=$((0x$HI - 0x$LO))
+  [ "$SZ" -ne 16384 ] && continue
+  VP=$(( (0x$LO + 0x80) / 4096 ))
+  ENT=$(sudo dd if=/proc/$PID/pagemap bs=8 skip=$VP count=1 2>/dev/null | xxd -e -g8 | awk '{print $2}')
+  [ -z "$ENT" ] && continue
+  PFN=$(( 0x$ENT & 0x7fffffffffffff ))
+  PA=$(( PFN * 4096 + 0x80 ))
+  echo "0x$LO 0x$(printf %x $PA)"
+done