Re: one more apic merging preliminary series

From: Ingo Molnar <mingo@elte.hu>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"macro@linux-mips.org" <macro@linux-mips.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
	Arjan van de Ven <arjan@infradead.org>,
	Yinghai Lu <yhlu.kernel@gmail.com>
Subject: Re: one more apic merging preliminary series
Date: Tue, 19 Aug 2008 02:21:42 +0200	[thread overview]
Message-ID: <20080819002142.GE9914@elte.hu> (raw)
In-Reply-To: <20080818203726.GB1152@linux-os.sc.intel.com>

* Suresh Siddha <suresh.b.siddha@intel.com> wrote:

> On Sun, Aug 17, 2008 at 05:45:40AM -0700, Ingo Molnar wrote:
> > 
> > * Cyrill Gorcunov <gorcunov@gmail.com> wrote:
> > 
> > > Please review - any comments are welcome!
> > >
> > > For now it's like code bloating - but it's just preliminary series to
> > > make apic_*.c code more or less similar. And it's still a bit far from
> > > being ready to be merged down.
> > 
> > applied to tip/x86/apic - thanks Cyrill.
> > 
> > Maciej's point about cleaning up the x2apic impact is very much true -
> > i've Cc:-ed Suresh and Venki. Even if we wont truly use x2apic in 32-bit
> > kernels, it's a piece of glue hardware that does not depend on which
> > mode the CPU is in, so support for it should be bitsize agnostic. It
> > will also obviously be good for test coverage, once x2apic capable hw
> > will be more widespread.
> 
> Interrupt-remapping(part of chipset) must be enabled before 
> enabling/using x2apic mode.
> 
> So, there is little bit more work (adding the intr-remapping pieces to 
> 32bit kernel etc) to be done, before enabling x2apic for 32-bit kernel 
> aswell.
> 
> I am planning to do some work (introduce some kind of 
> interrupt-remapping ops and cleanup some of the code in the existing 
> io_apic_64.c), that will eventually make it easy to add 
> interrupt-remapping and x2apic to 32bit aswell.

Yinghai unified io_apic.c in latest tip/master, and that means that the 
CONFIG_INTR_REMAP bit are now all in 32-bit code as well. It's not yet 
enabled in the Kconfig:

 config INTR_REMAP
        bool "Support for Interrupt Remapping (EXPERIMENTAL)"
        depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL

but it should be a lot less work now i suspect.

	Ingo