Date: Tue, 27 Sep 2005 09:51:03 -0600
From: Grant Grundler <grundler@parisc-linux.org>
To: Mikael Pettersson <mikpe@csd.uu.se>
Cc: Grant Grundler <grundler@parisc-linux.org>,
       "Randy.Dunlap" <rdunlap@xenotime.net>, linux-kernel@vger.kernel.org,
       akpm@osdl.org, greg@kroah.com, linux-pci@atrey.karlin.mff.cuni.cz,
       ak@suse.de
Subject: Re: [PATCH] MSI interrupts: disallow when no LAPIC/IOAPIC support
Message-ID: <20050927155103.GA9294@colo.lackof.org>
References: <20050926201156.7b9ef031.rdunlap@xenotime.net> <20050927044840.GA21108@colo.lackof.org> <20050926215245.7a1be7fa.rdunlap@xenotime.net> <20050927052128.GB21108@colo.lackof.org> <17209.3427.936263.463751@alkaid.it.uu.se>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <17209.3427.936263.463751@alkaid.it.uu.se>
User-Agent: Mutt/1.5.9i
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1007
Lines: 27

On Tue, Sep 27, 2005 at 11:14:11AM +0200, Mikael Pettersson wrote:
> Grant Grundler writes:
>  > Yeah, my preference would be PCI_MSI only depend on Local APIC.
>  > (Note that having a Local APIC implies having an IO APIC as well
> 
> Not true. Lots of systems have a local APIC but no I/O APICs.

Eh?!!!
Do systems with Local APIC still have IRQ lines going to the CPU?
How does PCI IRQ line otherwise generate an interrupt?

> However, having an I/O APIC pretty much implies having a local APIC.

Ok - That sounds right for x86 and is true for ia64.
parisc has IO SAPICs but no local APIC.

parisc and (IIRC) alpha has the functional equivalent of Local APIC
but the implementation details are different. ie they can't share
code with x86/ia64.

thanks,
grant
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/