On Mon, 20 Aug 2018, Arnd Bergmann wrote: > On Mon, Aug 20, 2018 at 4:17 PM Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > > On Sun, 19 Aug 2018, okaya@xxxxxxxxxxxxxx wrote: > > > > > +my new email > > > > > > On 2018-08-18 19:03, Arnd Bergmann wrote: > > > > On Sat, Aug 18, 2018 at 12:05 AM Maciej W. Rozycki <macro@xxxxxxxxxxxxxx> > > > > I think we need to identify the driver that is failing. > > > > It also may be some timing issue. > > > > I observed that not every kernel with the patch > > 92d7223a74235054f2aa7227d207d9c57f84dca0 fails, some of them get stuck > > only at boot, some get stuck only at shutdown, some not at all. Although > > all the kernels with this patch reverted work. > > > > So the patch may have uncovered some timing problem somewhere. > > > > x86 has the function io_delay that injects delays between I/O accesses for > > hardware that needs it - does alpha have something like this? > > The I/O delay would be very low on my list of possible root causes > for this, hardly any hardware at all relies on it, and all uses I see > are related to outb(), which you've already shown not to be the problem > with my test patch. > > Arnd The lockup happens somewhere in the function autoconfig in drivers/tty/serial/8250/8250_port.c, but I don't know where exactly because serial console doesn't work while the port is being probed. When I use console on a graphics card, the lockup doesn't happen. Mikulas
