Hi,
I have just discovered something that might be an unpredicted bug in Qt iOS. I
have an app which makes uses of inter app audio. Therefore, this app should be
able to jump and forth from host to app and vice versa. It should be also able
to make the jump with the lowest overhead as possible to avoid audio glitches.
Right now, what is concerning me the most is that after a couple of jumps,
which sometimes can be more or less, the app crashes. I was able to crash it
while running the debugger and this is what appeared in the stack trace:
libGPUSupportMercury.dylib`gpus_ReturnGuiltyForHardwareRestart:
0x18ef91f1c <+0>: orr w8, wzr, #0x1
0x18ef91f20 <+4>: movz w9, #0xdead, lsl #16
0x18ef91f24 <+8>: movk w9, #0xbeef
-> 0x18ef91f28 <+12>: str w9, [x8]
0x18ef91f2c <+16>: ret
The crashes thread was the QSGRenderThread. This seems to be a critical bug for
apps that need to behave this way, which I consider that is any professional
audio app nowadays. This happens on both Qt 5.5.1 and 5.6
Before filling a bug report I would like to share this info with the list and
have some insights about it.
Also, when the app starts I have some UIKit related warning. Not sure if they
related with the crash. Since I don’t write UI code for cocoa anymore since
using Qt/Qml, I deduce that this warnings come from Qt UIKit layer.
2016-04-05 00:17:37.131 DRC[307:14615] Unable to simultaneously satisfy
constraints.
Probably at least one of the constraints in the following list is one
you don't want.
Try this:
(1) look at each constraint and try to figure out which you
don't expect;
(2) find the code that added the unwanted constraint or
constraints and fix it.
(
"<NSLayoutConstraint:0x12d5cda80
V:|-(20)-[UIInputSetContainerView:0x12d5cd8e0] (Names:
'|':UITextEffectsWindow:0x12d6980d0 )>",
"<NSLayoutConstraint:0x12d692ea0 'UIInputWindowController-top'
V:|-(0)-[UIInputSetContainerView:0x12d5cd8e0] (Names:
'|':UITextEffectsWindow:0x12d6980d0 )>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x12d5cda80 V:|-(20)-[UIInputSetContainerView:0x12d5cd8e0]
(Names: '|':UITextEffectsWindow:0x12d6980d0 )>
Best regards,
Nuno
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