Re: perf hw in kexeced kernel broken in tip

Vivek Goyal
2010-12-01T19:47:18Z

On Wed, Dec 01, 2010 at 08:38:12PM +0100, Peter Zijlstra wrote:
> On Wed, 2010-12-01 at 11:23 -0500, Vivek Goyal wrote:
> > > What does kexec normally do to ensure hardware is left in a sane state?
> >
> > Typically calls device_shutdown() and sysdev_shutdown() from
> > kernel_restart_prepare() to shutdown the devices.
> >
> > Also calls machine_shutdown() which depending on architecture can take
> > care of various things like stopping other cpus, shutting down LAPIC,
> > disabling IOAPIC, disabling hpet, shutting down IOMMU etc
> > (native_machine_shutdown()).
>
> So basically there's no sane generic reset callout?

I think ->shutdown() calls are sane generic callouts. Isn't it?

There seem to be few exceptions for LAPIC, IOMMU and HPET and I am not
sure why they are not covered by shutdown calls. CCing Eric, he might
have more insight into it.

Thanks
Vivek