GPU hang file takes so long to read that the file gets deleted before I can copy it

Hello

I'm trying to debug a GPU hang in Spider-Man (mesa/mesa#11526), but it takes so long to copy the /sys/class/drm/card0/device/devcoredump/data file to the file system that the file gets deleted by xe 0000:00:02.0: [drm] Xe device coredump has been deleted. before my cp or cat finished. I haven't measured the exact speed, but it's in the range of kilobytes per MINUTE. Something really really wrong is going on here.

This is on LNL.

Edit: I was able to copy 46mb before the copy died. I tried with both 'cat' and 'cp' and I was always sending it to /root, so the transfer was not over serial console or baud modems.

Cc: @zehortigoza