Files
SDD a5769d3d2e dwt: GUI/X architecture note; Xlib callable but XOpenDisplay hangs
Static: the VT1200 GUI is an X11 dix server in ROM plus Xlib clients
(SERVER, SESSIONMGR/Terminal Manager, WM, VTE).  Internal clients use the
local service "xserver" via the display string "0::0"; TCP 6000 is a
separate authorised listener.  Function table and the 4-call hello-window
sequence are in dwt/notes/GUI_APPS.md.

Dynamic: a poke+jump payload proved the firmware ABI (strlen=4) and then
called XOpenDisplay; it never returns (stage 2, display 0, X-server client
watermark unchanged) and the rdebug service dies.  Verdict: hard for a
self-contained window; shared-RAM UI mutation (opcode 8) is the working
route.
2026-10-18 14:08:42 +03:00

35 lines
1.2 KiB
Lua

-- probe3.lua -- breakpoint on the X server connection-setup entry (Ghidra
-- 07EB1700) plus marker telemetry. If the server accepts an injected client,
-- an ACCEPT line appears; the boot's own clients prove the probe works.
local machine = manager.machine
local cpu = machine.devices[':maincpu']
local space = cpu.spaces['program']
local frame = 0
local function install()
local dbg = cpu.debug
if not dbg then print("probe3: no cpu.debug") return end
local ok, e = pcall(function()
dbg:bpset(0x3F58B800, "1", 'printf "probe3: ACCEPT pc=%08X\\n",pc; g')
end)
print("probe3: bpset accept=" .. tostring(ok) .. " " .. tostring(e))
end
local function u32(a)
local ok, v = pcall(function() return space:read_u32(a) end)
if ok then return v end
return 0xdeadbeef
end
emu.register_frame_done(function()
frame = frame + 1
if frame == 2 then install() end
if frame % 250 == 0 then
print(string.format("probe3: f=%d PC=%08X st=%d disp=%08X win=%08X wm=%d",
frame, cpu.state['PC'].value, u32(0x01850140), u32(0x01850100),
u32(0x01850120), u32(0x1b8620)))
end
end, "vt1200-gui-probe3")
if machine.debugger then machine.debugger.execution_state = 'run' end