Re: [edk2-devel] [edk2-staging/RiscV64QemuVirt PATCH V7 05/20] UefiCpuPkg: Add CpuTimerDxe module

["Sunil V L" <sunilvl@ventanamicro.com>]

On Thu, Feb 09, 2023 at 10:30:58AM +0000, Michael Brown wrote:
> On 09/02/2023 10:28, Sunil V L wrote:
> > > > +  gBS->RestoreTPL (OriginalTPL);
> > > > +  RiscVEnableTimerInterrupt (); // enable SMode timer int
> > > > +}
> > > 
> > > This design looks as though it does not support nested timer interrupts.
> > > The call to RestoreTPL() may invoke callbacks that may themselves include
> > > delay loops that wait upon further timer interrupts.  With the above code,
> > > those timer interrupts will never arrive since the timer interrupt is
> > > disabled at the point that you call RestoreTPL().
> > > 
> > > This will break device drivers such as those for USB network devices that
> > > rely on nested timer interrupts.
> > 
> > Thanks a lot for this feedback and background. We are aware of few issues
> > in this module. Currently, it is mostly porting what exists today in
> > edk2-platforms repo. We want to add all these additional fixes after
> > this basic thing is merged. That way we will have git history instead of
> > combining all fixes single commit. Andrei has a patch ready and waiting
> > for this to get merged. We can either combine this with his patch or
> > create one more.
> > 
> > Would that strategy be fine with you?
> 
> Sure, as long as someone other than me is keeping track of the need to fix
> this bug.  My work here is done.  :)
> 
Sure, I will keep track of this. We will need your help to review the changes.
Hope that is fine.

Thanks!
Sunil