Re: [PATCH 01/10] irqchip: irq-mips-gic: export gic_send_ipi

From: Jiang Liu
Date: Wed Aug 26 2015 - 22:22:56 EST

On 2015/8/27 5:40, Thomas Gleixner wrote:
> But back to the IPIs. We need infrastructure and DT support to:
> 1) reserve an IPI
> 2) send an IPI
> 3) request/free an IPI
> #1 We have no infrastructure for that, but we definitely need one.
> We can look at the IPI as a single linux irq number which is
> replicated on all cpu cores. The replication can happen in hardware
> or by software, but that depends on the underlying root irq
> controller. How that is implemented does not matter for the
> reservation.
> The most flexible and platform independent solution would be to
> describe the IPI space as a seperate irq domain. In most cases this
> would be a hierarchical domain stacked on the root irq domain:
> [IPI-domain] --> [GIC-MIPS-domain]
> on x86 this would be:
> [IPI-domain] --> [vector-domain]
> That needs some change how the IPIs which are used by the kernel
> (rescheduling, function call ..) are set up, but we get a proper
> management and collision avoidance that way. Depending on the
> platform we could actually remove the whole IPI compile time
> reservation and hand out IPIs at boot time on demand and
> dynamically.
Hi Thomas,
Good point:) That will make the code more clear.
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