Re: arm: DomU Networking enable leads to Dom0 kernel oops

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Sat, 25 Apr 2020, Julien Grall wrote:
> On Sat, 25 Apr 2020 at 10:49, Julien Grall <julien.grall.oss@xxxxxxxxx> wrote:
> >
> > On Sat, 25 Apr 2020 at 03:01, Stefano Stabellini <sstabellini@xxxxxxxxxx> 
> > wrote:
> > > [   86.900974] ------------[ cut here ]------------
> > > [   86.905134] Interrupt for port 6, but apparently not enabled; per-user 
> > > (____ptrval____)
> > > [   86.913228] WARNING: CPU: 0 PID: 2437 at drivers/xen/evtchn.c:167 
> > > evtchn_interrupt+0xfc/0x108
> >
> > The implementation of the evtchn_interrupt() is relying to be called
> > in the top-half. On RT, interrupts handlers are forced to be threaded
> > and use the IRQF_ONESHOT semantics if they were not threaded before.
> >
> > However, IRQF_ONESHOT is completely broken for event channels (this is
> > not RT's fault) and hence why you see the warning here.
> >
> > Note that you can't force to run evtchn_interrupt() in the top-half
> > because it relies on functions that may sleep.
> >
> > See https://lkml.org/lkml/2019/2/19/642.
> 
> Here at better link with the full conversation:
> 
> https://lore.kernel.org/lkml/5e256d9a-572c-e01e-7706-407f99245b00@xxxxxxx/

Many thanks for pointing it out to me. I think I know what the problem
is. I replied to that thread with a patch that fixes my LinuxRT issue on ARM:

https://marc.info/?l=xen-devel&m=158802965821440&w=2