Graphical corruption when using HalQuickRebootRoutine to return to dashboard

[abaire]

When using HalQuickRebootRoutine with a NULL szLaunchPath and a dwLaunchDataType of LDT_NONE (0xFFFFFFFF) there is a brief period of graphical corruption before the dashboard is displayed.

XVideoInit looks like it's doing reasonable things with respect to setting AvSetSavedDataAddress to the framebuffer so I'm not sure what is causing this.

• I do not see this corruption when doing a trivial launch of another nxdk-built XBE on the same data storage.
• I confirmed that I can grab the framebuffer via XVideoGetFB, memset it, flush it, and see the change reflected briefly before it's replaced by corruption.
• Reproduced both in xemu and on hardware, relatively trivial test program at https://github.com/abaire/nxdk_launch_test

[abaire]

Playing around with this a bit more, it seems that freeing the framebuffer set by the dashboard and retrieved via AvGetSavedDataAddress at

nxdk/lib/hal/video.c

Line 377 in f2c634f

MmPersistContiguousMemory(previousFB, previousFBSize, FALSE);

is what triggers the problem (if I comment out the lines unpersisting and freeing the previous FB the issue goes away).

I'm not sure if this is an indication that AvSetSavedDataAddress is somehow not working or if the kernel/dashboard/... just blindly uses the memory at 0x80061000 as the framebuffer when initializing the dashboard.