Hi Geert, IMHO - QEMU is irrelevant here. since I can do passthrough -- in fact -- many drivers do use timeout in .fb_sync e.g. i810fb_sync(), nouveau_fbcon_sync(), sm501fb_sync() etc.. I believe the correct behaviour should be a timeout wait instead of waiting indefinitely. - Tong
On Wed, Feb 24, 2021 at 6:35 AM Geert Uytterhoeven geert@linux-m68k.org wrote:
Hi Tong,
On Sun, Feb 21, 2021 at 1:05 AM Tong Zhang ztong0001@gmail.com wrote:
On Sat, Feb 20, 2021 at 6:33 PM Randy Dunlap rdunlap@infradead.org wrote:
On 2/20/21 3:02 PM, Tong Zhang wrote:
pm2fb_sync is called when doing /dev/fb read or write. The original pm2fb_sync wait indefinitely on hardware flags which can possibly stall kernel and make everything unresponsive. Instead of waiting indefinitely, we can timeout to give user a chance to get back control.
Is this a real problem or theoretical? Does someone still use this driver?
I currently have this problem on my machine. I have submitted a revised patch -- which includes the console log.
Your machine is "QEMU Standard"? Can this happen on real hardware, too, or is this a deficiency in QEMU, which should be fixed there?
Gr{oetje,eeting}s,
Geert-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds