Re: [RFC PATCH v2] Add IPI entry for CPU UP

From: Mark Rutland
Date: Tue Jan 12 2016 - 06:51:30 EST

On Tue, Jan 12, 2016 at 09:38:20AM +0000, Lorenzo Pieralisi wrote:
> On Tue, Jan 12, 2016 at 10:17:42AM +0800, Zhaoyang Huang wrote:
> > On 12 January 2016 at 10:05, Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx> wrote:
> > > In some ARM SOCs, IPI interrupt is used for hotplug in one cpu, that is,
> > > sending a IPI to the core in WFI and powerdown status. So Add a IPI
> > > entry for handle this kind of cpu up interrupt
> > > Launching the IPI can be done within PSCI, while there will be one unknown
> > > type of IPI as the dest core come up to the kernel world which will bring a
> > > warning so far.So add such type of IPI to handle the interrupt.
> You missed CC'ing ALKML for the second time and you were warned.
> You are adding a call to *send* an IPI in the kernel so the commit
> above is misleading.
> Acknowledge and clear the IRQ in FW so that the mechanism is completely
> implemented in FW (ie PSCI), that the CPU coming out of reset will run
> before getting to the kernel, this patch is not needed and we already
> explained to you why.
> Lorenzo

I would also suggest that FW used the set of SGIs reserved for secure
usage (i.e. ID8 - ID15), as these will not conflict with those the
kernel uses.