radeon 0000:00:01.0: Using 40-bit DMA addresses, meaning ?

[sdauth]

Hi,
I noticed this entry in my dmesg the other day while the system was under a lot of strain (above 20 load avg for hours and hours)
It showed up while or right after I played a video with mpv. (but certainly in that timeframe)
Actually, it happened before, while the system was under the same pressure.

It's a decade old APU (AMD A106800K with radeon hd 8670d for the gpu part)
There was no crash or anything, but does anyone know what it means ? ( In layman's terms ) Or if I should worry about it ?

Thanks.