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Diffstat (limited to 'tools/guest-diag/wall2/README-session77.md')
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diff --git a/tools/guest-diag/wall2/README-session77.md b/tools/guest-diag/wall2/README-session77.md index 03b0099..2fd77a6 100644 --- a/tools/guest-diag/wall2/README-session77.md +++ b/tools/guest-diag/wall2/README-session77.md @@ -605,3 +605,31 @@ timeout fire while a tracee is at a frequent-firing BP; prefer BPs that fire once or self-disable; prefer no-ptrace pollers for anything with a repeating pattern; the safe diagnostic is attach -> read -> detach without continue. + +**15. Session 94: THE INSTANCE CLEARS ARE REQUIRED (zero-gdb disproved); t104 is the safe form.** +Pure zero-gdb run (fresh r694, client + unwait.py ONLY, no gdb): unwait +wrote three +0x80 words and the client still ended `VKFAIL vkCreateDevice +... -4` - WITHOUT the instance-phase marker clears the device gate fails +even with the words. With t104.py (single BP at +0xB33D30; clears +u16@+0xe/+0xc/u32@+0; self-exits on cleared>=8 OR chits>=40 OR 25 s since +the last clear -> returns True so the script tail runs and batch gdb exits +cleanly, no outer-timeout dependence) + unwait + live_walk: CLEAR#1..#5, +two words written, client reached `VKINSTANCE ok / VKDEVS 2 / VKPICK / +VKDEVICE ok family=0` (r694 client 3725). The client then sat in the +post-device wait again; the t102 diagnostic could not attach because the +t104 gdb still held the slot (its 25 s-idle exit never fired - no +post-instance B33D30 hits - and its 150 s timeout likely fired at a stop += the known wedge risk). NEXT FORM: make t104 detach ITSELF from inside +the handler once the clears are done (`gdb.execute("detach")` from the +stop handler; the tracee resumes; the script ends and gdb exits) so NO +gdb is ever held while the client runs - then t102 always has the slot +and the wedge class disappears end-to-end. + +**16. The allocation/post-device phase is the remaining gate.** With +VKDEVICE green the client waits in a site that is neither the +0x80 word +pattern nor (likely) the A8 count path; the next session should (a) get +the detach-first t104 live, (b) run t102 immediately after VKDEVICE to +name the wait (read PC/bt/A8 count = base+0x2070b7c), and (c) inspect the +service for this client (pushes decoded / releases applied / counter +pub_calls) to see whether the allocation needs the live injections only +or a service-side gap. |