Debug Channels

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WINEDEBUG is an environment variable that turns debugging messages on or off.



class is optional and can be one of the following: err, warn, fixme, or trace. If class is not specified, all debugging messages for the specified channel are turned on. Each channel will print messages about a particular component of Wine. The following character can be either + or - to switch the specified channel on or off respectively. If there is no class part before it, a leading + can be omitted. Note that __spaces are not allowed any where in the string__.

channel specifies which debug channel to turn on or off. For complete list of channels run this command in the source dir

grep -r --include='*.c' --include='*.h' 'WINE_\(DEFAULT\|DECLARE\)_DEBUG_CHANNEL' dlls/ programs/

And with some more work we have sorted and formatted list in BASH (you may want to adjust number 26 near the end of this composite to match your indentation taste):

for modname in $(find dlls/ programs/ -mindepth 1 -type d | sort); do
  echo $(grep -rE --include='*.[ch]' '^WINE_(DEFAULT|DECLARE)_DEBUG_CHANNEL' $modname \
         | awk -F "[()]" '{print $2}' | sort | uniq) \
         | awk -v modname=$modname '{if (NF>0) printf("%-*s%s\n", 26, modname": ", $0)}';


will turn on all warning messages.
will turn on DLL warning messages and all heap messages.
will turn off all FIXME messages, turn on cursor warning messages, and turn on all relay messages (API calls).
will turn on all relay messages. For more control on including or excluding functions and dlls from the relay trace look into the [HKCU\Software\Wine\Debug] registry key (See Useful Registry Keys and the example below).

List of Debug Channels

accel acledit actctx activeds actxprxy adpcm advapi advpack alsa amstream
animate appbar appwizcpl aspi atl atom avicap avifile bidi bitblt
bitmap browseui button cabinet capi cards caret cdrom class clipboard
clipping clusapi cmd cmdlgtst combo comboex comm commctrl commdlg compstui
computername console coreaudio cred credui crtdll crypt cryptasn cryptdlg cryptdll
cryptnet cryptui ctapi32 curses cursor d3d d3d10 d3d11 d3d7 d3d8
d3d9 d3d_caps d3d_constants d3d_decl d3d_draw d3drm d3d_shader d3d_surface d3d_texture d3dx
d3dx8 d3dxof datetime dbghelp dbghelp_coff dbghelp_dwarf dbghelp_msc dbghelp_stabs dbghelp_symt dc
dciman ddeml ddraw ddraw_thunk debug_buffer debugstr devenum dialog dinput dll
dma dmband dmcompos dmdump dmfile dmfileraw dmime dmloader dmscript dmstyle
dmsynth dmusic dmusic32 dnsapi dosmem dpa dplay dpnet dpnhpast dpvoice
driver ds dsa dsalsa dscapture dsound dsound3d dssenh dswave dwmapi
dxdiag edit eject enhmetafile environ event eventlog exec explorer faultrep
fiber file fixup font fps fusion g711 gdi gdiplus global
glu gpkcsp graphics gstreamer handle header heap hid hlink hnetcfg
hook hotkey htmlhelp iccvid icm icmp icon imagehlp imagelist imm
imports inetcomm inetmib1 infosoft initpki inkobj inseng int int21 int31
io ipaddress iphlpapi itircl itss jack joystick jscript key keyboard
listbox listview loaddll local localspl localui lsa mapi mci mciavi
mcicda mcimidi mciwave mdi menu menubuilder message metafile midi mixer
mlang mmaux mmio mmsys mmtime module monthcal mountmgr mpeg3 mpr
mprapi msacm mscat mscms mscoree msdmo msftedit msg msgbox mshtml
msi msidb msiexec msimg32 msimtf msisip msisys msnet msrle32 mssip32
mstask msvcirt msvcr71 msvcrt msvcrt40 msvidc32 msvideo mswsock msxml nativefont
nddeapi netapi32 netbios newdev nls nonclient ntdll ntdsapi ntlm ntoskrnl
ntprint objsel odbc ole oleacc oledlg olemalloc olerelay olethk32 oleview
opengl openal32 pager palette pdh pidl powermgnt powrprof print printui
process profile progress propsheet propsys psapi psdrv pstores qcap qcap_v4l
qedit qmgr quartz query ras rebar recyclebin reg regedit region
relay resource resutils richedit richedit_check richedit_lists richedit_style rpc rpcss rundll32
sblaster sccbase schannel scroll secur32 seh selector sensapi server service
setupapi sfc share shdocvw shell shlctrl slbcsp slc snmpapi snoop
sound spoolss spoolsv start static statusbar storage stress string svchost
svrapi sxs sync synchronous syslevel system systray tab tape tapi
task text theming themingcombo thread threadpool thunk tid time timestamp
toolbar toolhelp tooltips trackbar trash treeview twain typelib typelib2 uninstaller
uniscribe updown url urlmon user userenv uxtheme variant vdmdbg ver
virtual volume vxd wave wavemap wc_font wgl win wineboot winebrowser
winecfg wineconsole wine_d3d winedbg winedevice winemine winevdm wing winhelp winhttp
wininet winmm winscard winsock winspool winstation wintab wintab32 wintrust wldap32
wnet wtsapi x11drv x11settings xcopy xdg xdnd xrandr xrender xvidmode

Useful Channels

Some of the debug channels can be particularly useful:

  • +all : logs everything, probably gives too much information in most cases, but may come in handy for subtle issues
  • +heap : traces all heap activity in the program and switches on constant integrity checks. If an app is trashing the heap, doing a +relay,+heap trace will let you narrow down exactly where it's happening. If an inconsistency is detected, Wine will dump the contents of the heap and terminate the program. Although many things can lead to trashing the heap, the most common is Wine overrunning an internal buffer. Be sure to remember this channel; most new Wine code uses the !HeapAlloc/HeapFree APIs internally, and a primary reason is that Wine's built in heap debugging is so useful.
  • +loaddll : reports each DLL as it's loaded. This is a good, lightwei-ght alternative if you don't have the Windows program Dependency Walker available.
  • +message : logs Windows messages
  • +msgbox : logs when message boxes are displayed
  • +olerelay : dumps calls made through the typelibrary marshaller. It's a bit like +relay but works for a certain class of DCOM calls that wouldn't normally show up. Unfortunately, while this can be useful especially for debugging InstallShield or DCOM issues, this isn't a general COM relay mechanism. Since InstallShield/DCOM issues are quite advanced, it's recommended you ask for help if you want to try using this channel.
  • +relay : logs every call that crosses the DLL boundary of Wine's built-in modules, including calls between (non-native) DLLs. This channel is often the first port of call when you have no idea what's going wrong. It shows you each call into and out of Wine modules at the DLL boundaries. If you're being overwhelmed by certain functions, look into setting the RelayInclude and RelayExclude strings in the Wine registry (under [HKCU\Software\Wine\Debug]). A good initial value for !RelayExclude is:
These functions are called a lot, but don't usually give any clues as to why a program might be failing.
  • +seh : logs Windows exceptions (Structured Exception Handling). These are invoked either when an application performs an illegal operation (i.e. crashes), or if a program throws its own exceptions. Wine converts UNIX signals into SEH exceptions and outputs them using this channel. This can be useful because applications will often trap their own crash, in order to perform an emergency save for instance. The most common exception to watch for is STATUS_ACCESS_VIOLATION or 0xC0000005 which is the closest equivalent in Win32 to a segfault. You may also see codes which don't appear in the headers; these are typically language-specific exceptions used by whichever compiler was used to produce the EXE. E.g. 0xEEDFADE is the code for a Delphi internal exception, and 0xE06D7363 is a Microsoft Visual C++ exception, which has a magic value ({{{info[0]}}}) of 0x19930520, which is easy to remember because it looks like a date (and probably is). If you see any of these exceptions, it probably means a Win32 API call returned a non-zero error code somewhere.
  • +server : shows each wineserver RPC. You don't normally need this but it may prove helpful when debugging wineserver issues.
  • +snoop : logs every function call between native DLLs. This is similar to +relay but works between two native DLLs, although this channel provides poorer information because parameters aren't reported. +snoop may also break or destabilize an application as it inspects the stack and disassembles function prologues to try and guess parameters.
  • +synchronous : forces X11 into synchronous mode
  • +tid : prefixes each debug output line with the ID of the thread that generated it. This is invaluable for debugging multithreaded applications since a context switch can occur at any time and without it, there's often no way to tell exactly what's going on inside the program. If you aren't sure if a program is concurrent, enable it anyway. Although no channel is free, this one has a very cheap processing cost, and you can always disable it if you're only seeing one thread.
  • +timestamp: prefixes each debug output line with the timestamp when that line executed. This is invaluable for debugging performance issue.

Other Debugging Tips

  • If a program is displaying a message box when it fails, and you don't know what is causing the problem, try performing a +relay,+msgbox trace. Then open the debug log in your favourite editor or text viewer (less is quite good) and search for trace:msgbox. Look at the relay data before the MessageBox API call, although the problem may not be caused by a call that happens immediately before the error. Keep an eye out for failing API calls in particular, and remember that there's little consistency in the Windows API as to what return codes mean. You just have to get used to what the specific API uses, and while many return non-zero for success and zero for fail, some use the opposite convention.
  • If a program fails at startup with nothing to suggest why, you can use an +all trace. If your program seems to be failing a long way from an API call, you might also try [:Disassembly: disassembling] it to see if it's accessing some of the parameters passed in to !WinMain (for instance, Dungeon Keeper crashes if you run it without an absolute path for argv[0]).
  • If your logs are becoming too big to work with, try applying the [:Debug_trace_toggle_key: debug delay patch]. It lets you toggle logging on and off with the F12 key and also control the debug channels from within the source by using the libwine APIs.

Making +relay less verbose

If you're looking for a problem that happens a couple minutes into the run of an app, +relay can be too verbose. In that case, run it once, then send the log through a script like

# Make grep go fast
# Find top ten calls
freq=`grep ':Ret ' | sed 's/(.*//;s/.* //' | sort | uniq -c | sort -n | tail | awk '{print $2}' | tr '\012' ';'`
cat > quiet.reg << _EOF



wine regedit quiet.reg

This will tell Wine to not log the ten most frequent calls in your app, which should make your +relay log much more managable in size.

See Also