Details
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Bug
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Resolution: Unresolved
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P2: Important
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None
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6.3.1
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None
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Fedora 37, libdrm 2.4.112, libwayland-egl 1.21.0, mesa 22.2.3
AMD 4700U integrated graphics
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Linux/Wayland
Description
Originally discovered in Qt5 as part of https://bugreports.qt.io/browse/QTBUG-82528 however as the relevant interfaces have changed for Qt6, I am opening a new issue for that specifically.
Crux is that this code (full reproducer attached) fails to create the native context
QOpenGLContext *context = new QOpenGLContext(); context->create(); auto egl = context->nativeInterface<QNativeInterface::QEGLContext>(); QOpenGLContext *native = egl->fromNative (egl->nativeContext(), egl->display());
From a quick trip through the debugger, on my local system there seems to be a dynamic_cast that fails in this case inside the QNativeInterface::QEGLContext::fromNative() function.
(gdb) disassemble
Dump of assembler code for function _ZN16QNativeInterface11QEGLContext10fromNativeEPvS1_P14QOpenGLContext:
0x00007ffff72fbc10 <+0>: endbr64
0x00007ffff72fbc14 <+4>: mov 0x1e5d45(%rip),%rax # 0x7ffff74e1960
0x00007ffff72fbc1b <+11>: push %r12
0x00007ffff72fbc1d <+13>: push %rbp
0x00007ffff72fbc1e <+14>: push %rbx
0x00007ffff72fbc1f <+15>: mov %rdi,%rbx
0x00007ffff72fbc22 <+18>: mov (%rax),%rdi
0x00007ffff72fbc25 <+21>: test %rdi,%rdi
0x00007ffff72fbc28 <+24>: je 0x7ffff72fbc70 <_ZN16QNativeInterface11QEGLContext10fromNativeEPvS1_P14QOpenGLContext+96>
0x00007ffff72fbc2a <+26>: mov %rsi,%rbp
0x00007ffff72fbc2d <+29>: mov %rdx,%r12
0x00007ffff72fbc30 <+32>: mov 0x1e5831(%rip),%rsi # 0x7ffff74e1468
0x00007ffff72fbc37 <+39>: mov 0x1e6032(%rip),%rdx # 0x7ffff74e1c70
0x00007ffff72fbc3e <+46>: mov $0xfffffffffffffffe,%rcx
0x00007ffff72fbc45 <+53>: call 0x7ffff6d4b0d0 <__dynamic_cast@plt>
0x00007ffff72fbc4a <+58>: mov %rax,%rdi
0x00007ffff72fbc4d <+61>: test %rax,%rax
=> 0x00007ffff72fbc50 <+64>: je 0x7ffff72fbc70 <_ZN16QNativeInterface11QEGLContext10fromNativeEPvS1_P14QOpenGLContext+96>
0x00007ffff72fbc52 <+66>: mov (%rax),%rax
0x00007ffff72fbc55 <+69>: mov %r12,%rcx
0x00007ffff72fbc58 <+72>: mov %rbp,%rdx
0x00007ffff72fbc5b <+75>: mov %rbx,%rsi
0x00007ffff72fbc5e <+78>: pop %rbx
0x00007ffff72fbc5f <+79>: pop %rbp
0x00007ffff72fbc60 <+80>: mov 0x10(%rax),%rax
0x00007ffff72fbc64 <+84>: pop %r12
0x00007ffff72fbc66 <+86>: jmp *%rax
0x00007ffff72fbc68 <+88>: nopl 0x0(%rax,%rax,1)
0x00007ffff72fbc70 <+96>: pop %rbx
0x00007ffff72fbc71 <+97>: xor %eax,%eax
0x00007ffff72fbc73 <+99>: pop %rbp
0x00007ffff72fbc74 <+100>: pop %r12
0x00007ffff72fbc76 <+102>: ret
End of assembler dump.
(gdb) info registers
rax 0x0 0
rbx 0x5bbe80 6012544
rcx 0x435e50 4415056
rdx 0x0 0
rsi 0x7fffffffd650 140737488344656
rdi 0x0 0
rbp 0x5771f0 0x5771f0
rsp 0x7fffffffd6a0 0x7fffffffd6a0
r8 0x435e50 4415056
r9 0x7ffff74cb7d8 140737342388184
r10 0x3c 60
r11 0x7ffff72fbc10 140737340488720
r12 0x0 0
r13 0x1 1
r14 0x403db0 4210096
r15 0x7ffff7ffd000 140737354125312
rip 0x7ffff72fbc50 0x7ffff72fbc50 <QNativeInterface::QEGLContext::fromNative(void*, void*, QOpenGLContext*)+64>
eflags 0x246 [ PF ZF IF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
(gdb) ni
0x00007ffff72fbc70 in QNativeInterface::QEGLContext::fromNative (context=0x5bbe80, display=<optimized out>, shareContext=<optimized out>) at /usr/src/debug/qt6-qtbase-6.3.1-4.fc37.x86_64/src/gui/platform/unix/qunixnativeinterface.cpp:167
167 }