I would like to thank you all for your help. now, debian supports big navi graphics cards.
to start with, "navy21" cards are supported. AMD RX 6800 /6800 XT /6900 XT The 6700 and, perhaps, the 6500 are still to come.With gcn3.0 support now enabled, it is likely that the RX 6x00 generation will be fully supported.
remains a question : how did you know where the error came from ? and what to modify ?
respectfully . alain. p.s. you can close this thread.
