Re: tests/qtest: Is vnc-display-test supposed to work on Darwin?

["Daniel P. Berrangé" <berrange@redhat.com>]

On Thu, Jan 19, 2023 at 12:49:48PM +0100, Philippe Mathieu-Daudé wrote:
> On 19/1/23 12:33, Daniel P. Berrangé wrote:
> > On Thu, Jan 19, 2023 at 12:21:58PM +0100, Philippe Mathieu-Daudé wrote:
> > > On 19/1/23 12:16, Daniel P. Berrangé wrote:
> > > > On Thu, Jan 19, 2023 at 12:01:18PM +0100, Philippe Mathieu-Daudé wrote:
> > > > > On 5/12/22 08:51, Marc-André Lureau wrote:
> > > > > > On Fri, Dec 2, 2022 at 1:51 PM Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
> > > > > > > 
> > > > > > > The vnc-display-test is failing on Darwin:
> > > > > > > 
> > > > > > > tests/qtest/vnc-display-test:45038): ERROR **: 10:42:35.488: vnc-error:
> > > > > > > Unsupported auth type 17973672
> > > > > > 
> > > > > > It is supposed to pass. Can you share more details? It doesn't look
> > > > > > like an endianness issue, at first sight..
> > > > > 
> > > > > Adding '-trace vnc*' and setting _VNC_DEBUG in "vnc.h" I get:
> > > 
> > > > > Bail out! FATAL-ERROR: vnc-error: Unsupported auth type 5489072
> > > > 
> > > > ^^^^ This specific message is comnig from the gtk-vnc client rather
> > > > than QEMU
> > > > 
> > > > Still doesn't tell us if the flaw is server or client side. The
> > > > logs from QEMU are insufficient. In theory it should be reporting
> > > > auth type == 0 though, for 'no auth' configs.
> > > 
> > > > > Does that help? What else can I do to gather more info?
> > > > 
> > > > Modify vnc-display-test.c to call  vnc_util_set_debug(TRUE);
> > > > before vnc_connection_new(), to get the gtk-vnc debug logs
> > > > to stderr too.
> > > Here you go:
> > > 
> > > vnc_server_dpy_recreate VNC server dpy recreate dpy=0x1588b8000 size=640x384
> > > fmt=537004168
> > > vnc_auth_init VNC auth init state=0x1588b8000 websock=0 auth=1 subauth=0
> > > vnc_auth_init VNC auth init state=0x1588b8000 websock=1 auth=1 subauth=0
> > > vnc_client_connect VNC client connect state=0x1484b0000 ioc=0x152e667f0
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Init VncConnection=0x14f0168b0
> > > gtk-vnc-DEBUG: 12:20:30.482: ../src/vncconnection.c Init
> > > VncConnection=0x14f0168b0
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Thinking about auth type 1
> > > gtk-vnc-DEBUG: 12:20:30.482: ../src/vncconnection.c Thinking about auth type
> > > 1
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Decided on auth type 1
> > > gtk-vnc-DEBUG: 12:20:30.482: ../src/vncconnection.c Decided on auth type 1
> > 
> > So here we set conn->auth_type == 1
> > 
> > 
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Open fd=4
> > > gtk-vnc-DEBUG: 12:20:30.482: ../src/vncconnection.c Open fd=4
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Open coroutine starting
> > > gtk-vnc-DEBUG: 12:20:30.482: ../src/vncconnection.c Open coroutine starting
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Started background coroutine
> > > gtk-vnc-DEBUG: 12:20:30.484: ../src/vncconnection.c Started background
> > > coroutine
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Connecting to FD 4
> > > gtk-vnc-DEBUG: 12:20:30.484: ../src/vncconnection.c Connecting to FD 4
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Emit main context 16
> > > gtk-vnc-DEBUG: 12:20:30.485: ../src/vncconnection.c Emit main context 16
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Protocol initialization
> > > gtk-vnc-DEBUG: 12:20:30.485: ../src/vncconnection.c Protocol initialization
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Schedule greeting timeout
> > > 0x14f0155e0
> > > gtk-vnc-DEBUG: 12:20:30.485: ../src/vncconnection.c Schedule greeting
> > > timeout 0x14f0155e0
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Remove timeout 0x14f0155e0
> > > gtk-vnc-DEBUG: 12:20:30.485: ../src/vncconnection.c Remove timeout
> > > 0x14f0155e0
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Server version: 3.8
> > > gtk-vnc-DEBUG: 12:20:30.485: ../src/vncconnection.c Server version: 3.8
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Sending full greeting
> > > gtk-vnc-DEBUG: 12:20:30.485: ../src/vncconnection.c Sending full greeting
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Using version: 3.8
> > > gtk-vnc-DEBUG: 12:20:30.485: ../src/vncconnection.c Using version: 3.8
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Possible auth 1
> > > gtk-vnc-DEBUG: 12:20:30.589: ../src/vncconnection.c Possible auth 1
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Emit main context 14
> > > gtk-vnc-DEBUG: 12:20:30.589: ../src/vncconnection.c Emit main context 14
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Waiting for auth type
> > > gtk-vnc-DEBUG: 12:20:30.589: ../src/vncconnection.c Waiting for auth type
> > > # gtk-vnc-DEBUG: ../src/vncconnection.c Choose auth 10486192
> > 
> > Here we've read conn->auth_type and got back 10486192 nonsense instead
> > of 1.
> > 
> > Interestingly this value is differetn from the previous debug log
> > which reported  5489072, so i guess we're getting garbage here for
> > unknown reasons.
> > 
> > This looks like a gtk-vnc problem rather than QEMU.
> > 
> > I'm a little worried that perhaps the gtk-vnc ucontext coroutine backend
> > is broken on macOS
> > 
> > What coroutine backend does QEMU end up using on macOS ? Is it the
> > sigaltstack one ?
> 
>   Block layer support
>     coroutine backend            : sigaltstack
>     coroutine pool               : YES
> 
> When trying the coroutine options, with --with-coroutine=windows:
> 
> ERROR: 'windows' coroutine backend only valid for Windows
> 
> :) and with --with-coroutine=ucontext I get:
> 
> ERROR: 'ucontext' backend requested but makecontext not available
> 
> config.log hints:
> 
> /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/ucontext.h:51:2:
> error: The deprecated ucontext routines require _XOPEN_SOURCE to be defined
> #error The deprecated ucontext routines require _XOPEN_SOURCE to be defined
>  ^
> 
> Adding _XOPEN_SOURCE to QEMU_CFLAGS:
> 
> warning: 'makecontext' is deprecated: first deprecated in macOS 10.6 - No
> longer supported [-Wdeprecated-declarations]
> /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/ucontext.h:41:6:
> note: 'makecontext' has been explicitly marked deprecated here
> void makecontext(ucontext_t *, void (*)(), int, ...);
>      ^
> 
> So to detect makecontext() I have to add
> --extra-cflags=-mmacosx-version-min=10.5 but then linking fails with
> multiple "$LIBNAME was built for newer macOS version (13.0) than being
> linked (11.0)".

Yes, ucontext has been deprecated forever on macOS, but in practice it
has still been functional if you define _XOPEN_SOURCE, which is what
gtk-vnc has done traditionally.

I presume this is on the aarch64 macOS though, and so all bets are off
wrt ucontext backend unless someone knows it works correctly with the
m1 port. I fear that's not the case though, given the wierd error
scenario we're hitting in gtk-vnc.

I might need to add a sigaltstack impl to gtk-vnc

With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|