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| author | Arthur Hanson Rasmusson <arthur@vgpu.io> | 2026-10-25 09:08:22 -0400 |
|---|---|---|
| committer | Arthur Hanson Rasmusson <arthur@vgpu.io> | 2026-10-25 09:08:22 -0400 |
| commit | 7554ae4b029b5a1df98d26b40dab58ea9630e645 (patch) | |
| tree | 5a17ec59006201783d16cd87d7800b0867e26378 /tools | |
| parent | 09730aadb70ffda15b8e1c55fbb7322c9e0926a5 (diff) | |
| download | open-iov-7554ae4b029b5a1df98d26b40dab58ea9630e645.tar.gz open-iov-7554ae4b029b5a1df98d26b40dab58ea9630e645.zip | |
wall-2 session-82: counter-page PA hunt - the client's pagemap does not contain the counter pool (guest_pmap_win.py empty for 0x20400f000 and 0x121000000 ranges; semfix_uvmt's pin_counter_page never succeeded) and the vidmem-window hypothesis is not supported (poke_vidmem at the pool window offset 0x3F87000 + rank slots 0xfd0/0xfc0/0xfb0 with 6 then 0x40 changed the shadow but did not move the A8 wait); gdb attach hangs on the post-device spin (kill by PID + SIGCONT recovery)
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/guest-diag/wall2/README-session77.md | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/tools/guest-diag/wall2/README-session77.md b/tools/guest-diag/wall2/README-session77.md index 82e162b..891ef42 100644 --- a/tools/guest-diag/wall2/README-session77.md +++ b/tools/guest-diag/wall2/README-session77.md @@ -183,3 +183,25 @@ * The rank slots for the GL client's channels (handles 0xbeec0100, 0xbeec0104, 0xbeee0100 -> ranks 0,1,2): 0x20400ffd0 / 0x20400ffc0 / 0x20400ffb0. + +## ADDENDUM (r686, session 82) — the counter-page PA hunt: pagemap route confirmed dead, vidmem-window hypothesis tested and not supported + +* The client's own pagemap does NOT contain the counter pool: the + semfix_uvmt tool's resolver (`guest_pmap_win.py <pid> 0x20400f000 + 0x204010000 64`) returns NOTHING, as does the UVM pool range + (`0x121000000 0x121100000`). The tool's `pin_counter_page` has + therefore never succeeded for these clients (the STALL WATCHDOG's + "re-pin counter" attempts across sessions produced no "counter: + pinned" line). +* VIDMEM-window hypothesis tested: the counter VA 0x20400f000 is in the + emulated vidmem window (>= SVC_VIDMEM_VA_BASE 0x200080000), so its + window offset is 0x3F87000 (0x20400f000 - 0x200080000). The shadow + there is reachable and all-zero (`sema_vidmem_dump 0x3f87000,64`); + poking the rank slots (+0xfd0/+0xfc0/+0xfb0 = ranks 0/1/2) with 6 and + then 0x40 via `poke_vidmem` changed the shadow (verified by dump) but + did NOT move the client's wait. The vidmem route is not (or not only) + the completion path; the A8 loop's tables have another source. +* gdb-attach hazard (again): attaches to the client in its post-device + spin hang with no output; two gdb chains had to be killed by PID + (never a pattern) and the client SIGCONT'd. Probe only while the + client is in do_poll. |