From: "H. Peter Anvin" <hpa@zytor.com>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
"ebiederm@xmission.com" <ebiederm@xmission.com>,
Yinghai Lu <yinghai@kernel.org>,
"Maciej W. Rozycki" <macro@linux-mips.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [patch] x86, apic: use 0x20 for the IRQ_MOVE_CLEANUP_VECTOR instead of 0x1f
Date: Mon, 11 Jan 2010 14:57:14 -0800 [thread overview]
Message-ID: <4B4BACCA.2040805@zytor.com> (raw)
In-Reply-To: <1263250418.2859.681.camel@sbs-t61.sc.intel.com>
On 01/11/2010 02:53 PM, Suresh Siddha wrote:
>
>> However, my most serious concern with this patch is that there is a
>> fairly significant change due to this patch, which is that the legacy
>> IRQ vectors now fall *inside* the FIRST_DEVICE_VECTOR range. This isn't
>> a bad thing -- in fact, it is fundamentally the right thing to do
>> especially once we consider platforms which *don't* have the legacy IRQs
>> -- but it makes me scared of unexpected behavior changes as a result.
>> If you feel confident that that is not the case, could you outline why
>> it shouldn't be a problem?
>
> In irqinit.c, we statically pre-assign the per-cpu vector to irq
> mappings (vector_irq) for all the legacy IRQ vectors. Similarly irq_cfg
> is statically initialized for legacy IRQ's in io_apic.c. So we won't be
> able to use this space for anything else.
>
What enforces that, though? The used_vector bitmap? In the past it was
enforced simply by being < FIRST_DEVICE_VECTOR.
-hpa
next prev parent reply other threads:[~2010-01-11 22:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-09 2:09 [patch] x86, apic: use 0x20 for the IRQ_MOVE_CLEANUP_VECTOR instead of 0x1f Suresh Siddha
2010-01-09 2:19 ` H. Peter Anvin
2010-01-09 2:50 ` Yinghai Lu
2010-01-11 22:53 ` Suresh Siddha
2010-01-11 22:57 ` H. Peter Anvin [this message]
2010-01-11 23:10 ` Eric W. Biederman
2010-01-11 23:13 ` H. Peter Anvin
2010-01-12 0:06 ` Suresh Siddha
2010-01-12 0:13 ` H. Peter Anvin
2010-01-12 0:28 ` Eric W. Biederman
2010-01-12 0:36 ` H. Peter Anvin
2010-01-12 1:52 ` Eric W. Biederman
2010-01-12 2:17 ` H. Peter Anvin
2010-01-12 2:27 ` Eric W. Biederman
2010-01-12 10:25 ` Alan Cox
2010-01-13 20:36 ` Eric W. Biederman
2010-01-13 20:38 ` H. Peter Anvin
2010-01-13 20:53 ` H. Peter Anvin
2010-01-13 20:58 ` H. Peter Anvin
2010-01-12 0:42 ` H. Peter Anvin
2010-01-11 23:00 ` Eric W. Biederman
2010-01-11 23:07 ` H. Peter Anvin
2010-01-09 3:07 ` Yinghai Lu
2010-01-09 3:20 ` H. Peter Anvin
2010-01-09 3:23 ` H. Peter Anvin
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