Slater
Headphoneus Supremus
I get the refill handler panic. But only now and again.
Can't help on the *PANIC* TLB refill handler issue.
From a generic non-Rockbox point of view, TLB refilling is a memory management function which is handled by the main processor.
According to this post (http://forums.rockbox.org/index.php?topic=17245.30) on the Rockbox forums, it appears that it's likely caused by some bug in the code. Even though that Rockbox thread is from 2008, it references players using the same Ingenic Jz47xx series of CPUs that the Xduoo X3 uses (X3 just using the more current version Ingenic JZ4760B as referenced https://www.rockbox.org/wiki/XDuooX3 and https://www.rockbox.org/wiki/IngenicJz47xx). The RB developer 'mcuelenaere' appears to have later corrected the issue (due to a typo in the code), as indicated by his 2nd post down.
That does't mean it's the exact same cause of the *PANIC* TLB refill handler crash on the XDuoo X3 code, but at least it's something to go on. The fact that the Rockbox thread is in the 'New Ports' section, could indicate that mcuelenaere's (corrected) code may not be part of the main Rockbox code. I don't know what version of the code XVortex is using as his base code, but that would be a good place to start IMO.
I wish I was an application developer so I could help more (I'm just IT Admin/DevOps who've supported developers for 20 yrs, so I'm used to assisting tracking down bugs), but perhaps XVortex will see this post and have a clue; maybe contact 'mcuelenaere', etc.