From: Grant Likely <grant.likely@secretlab.ca>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch@vger.kernel.org, Linus Torvalds <torvalds@osdl.org>,
Andrew Morton <akpm@linux-foundation.org>,
x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Paul Mundt <lethal@linux-sh.org>,
Russell King <linux@arm.linux.org.uk>,
David Woodhouse <dwmw2@infradead.org>,
Jesse Barnes <jbarnes@virtuousgeek.org>,
Yinghai Lu <yinghai@kernel.org>
Subject: Re: [patch 46/47] powerpc: Use new irq allocator
Date: Mon, 4 Oct 2010 10:46:00 -0600 [thread overview]
Message-ID: <20101004164600.GB13749@angua.secretlab.ca> (raw)
In-Reply-To: <1286146459.2463.308.camel@pasglop>
On Mon, Oct 04, 2010 at 09:54:19AM +1100, Benjamin Herrenschmidt wrote:
> On Sun, 2010-10-03 at 09:53 -0700, Eric W. Biederman wrote:
> > Thomas Gleixner <tglx@linutronix.de> writes:
> >
> > >> That would make things much cleaner and in fact move one large step
> > >> toward being able to make powerpc virq scheme generic, which seems to be
> > >> a good idea from what I've heard :-)
> > >
> > > Yep.
> >
> > I'm not certain about making the ppc virq scheme generic. Maybe it is
> > just my distorted impression but I have the understanding that ppc irq
> > numbers mean nothing and are totally unstable whereas on x86 irq numbers
> > in general are stable (across kernel upgrades and changes in device
> > probe order) and the irq number has a useful hardware meaning. Which
> > means you don't have to go through several layers of translation tables
> > to figure out which hardware pin you are talking about.
[...]
>
> The main deal I'd say is that in embedded land (and to some extent I
> suspect that's going to happen more with x86), you quickly end up with
> multiple interrupt domains, via cascaded controllers of all kinds etc...
[...]
> - Appart from the risk of breaking crap that parses /proc/interrupts,
> adding the HW irq information there would be trivial and solve your
> problem.
>
> So overall, I don't see a problem at all. And it makes handling of
> arbitrary combinations of interrupt domains (cascaded PICs) very very
> easy indeed.
Right, the stability of irq numbers is more of a user-interface
problem than a technical deficiency with virq, and a solvable one at
that. If fact, I'd go as far as saying that having irq numbers mean
nothing is a *virtue* of the approach because it forces developers to
look at the real irq controller attachment rather than some
hwirq==linux-irq assumption.
As mentioned in my other reply, I'd be perfectly happy to stop exposing
linux irq numbers to userspace entirely, but I realize that would
break /proc/interrupts users. However, I do completely agree that
exposing the hwirq information is very much required.
g.
next prev parent reply other threads:[~2010-10-04 16:46 UTC|newest]
Thread overview: 158+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-30 23:14 [patch 00/47] Sparse irq rework Thomas Gleixner
2010-09-30 23:14 ` [patch 01/47] x86: Plug memory leak in sparse irq Thomas Gleixner
2010-09-30 23:14 ` [patch 02/47] x86: Hpet: Fix bogus error check in hpet_assign_irq() Thomas Gleixner
2010-09-30 23:14 ` Thomas Gleixner
2010-09-30 23:14 ` [patch 03/47] genirq: Provide status modifier Thomas Gleixner
2010-09-30 23:14 ` Thomas Gleixner
2010-09-30 23:14 ` [patch 04/47] arm: Use irq " Thomas Gleixner
2010-09-30 23:14 ` Thomas Gleixner
2010-09-30 23:14 ` [patch 05/47] genirq-sanitize-irq-data-accessors.patch Thomas Gleixner
2010-09-30 23:14 ` Thomas Gleixner
2010-09-30 23:15 ` [patch 06/47] genirq: Distangle kernel/irq/handle.c Thomas Gleixner
2010-09-30 23:15 ` Thomas Gleixner
2010-09-30 23:15 ` [patch 07/47] genirq: Remove early_init_irq_lock_class() Thomas Gleixner
2010-09-30 23:15 ` Thomas Gleixner
2010-09-30 23:15 ` [patch 08/47] genirq: Move core only inlines to kernel/irq Thomas Gleixner
2010-09-30 23:15 ` [patch 09/47] isdn: hisax: Replace the bogus access to irq stats Thomas Gleixner
2010-09-30 23:15 ` Thomas Gleixner
2010-09-30 23:15 ` [patch 10/47] genirq: Remove export of kstat_irqs_cpu Thomas Gleixner
2010-09-30 23:15 ` [patch 11/47] genirq: Provide default irq init flags Thomas Gleixner
2010-09-30 23:15 ` Thomas Gleixner
2010-09-30 23:15 ` [patch 12/47] arm: Use ARCH_IRQ_INIT_FLAGS Thomas Gleixner
2010-09-30 23:15 ` [patch 13/47] powerpc: " Thomas Gleixner
2010-09-30 23:15 ` Thomas Gleixner
2010-09-30 23:15 ` [patch 14/47] genirq: Implement a sane sparse_irq allocator Thomas Gleixner
2010-09-30 23:15 ` Thomas Gleixner
2010-10-01 5:28 ` Yinghai Lu
2010-10-01 20:36 ` Thomas Gleixner
2010-09-30 23:15 ` [patch 15/47] genirq: Prepare proc for real sparse irq support Thomas Gleixner
2010-09-30 23:15 ` [patch 16/47] genirq: Implement sane enumeration Thomas Gleixner
2010-09-30 23:15 ` Thomas Gleixner
2010-10-03 10:55 ` Grant Likely
2010-09-30 23:15 ` [patch 17/47] genirq-update-kerneldoc.patch Thomas Gleixner
2010-09-30 23:15 ` Thomas Gleixner
2010-09-30 23:16 ` [patch 18/47] genirq: Use sane sparse allocator Thomas Gleixner
2010-09-30 23:16 ` Thomas Gleixner
2010-09-30 23:16 ` [patch 19/47] genirq: Query arch for number of early descriptors Thomas Gleixner
2010-09-30 23:16 ` Thomas Gleixner
2010-09-30 23:16 ` [patch 20/47] x86: Remove useless reinitialization of irq descriptors Thomas Gleixner
2010-09-30 23:16 ` Thomas Gleixner
2010-10-03 15:21 ` Eric W. Biederman
2010-10-03 18:26 ` Thomas Gleixner
2010-09-30 23:16 ` [patch 21/47] x86: Sanitize apb timer interrupt handling Thomas Gleixner
2010-09-30 23:16 ` Thomas Gleixner
2010-09-30 23:16 ` [patch 22/47] x86: lguest: Convert to new irq chip functions Thomas Gleixner
2010-09-30 23:16 ` [patch 23/47] x86: Cleanup visws interrupt handling Thomas Gleixner
2010-09-30 23:16 ` Thomas Gleixner
2010-09-30 23:16 ` [patch 24/47] x86: i8259: Convert to new irq_chip functions Thomas Gleixner
2010-09-30 23:16 ` Thomas Gleixner
2010-09-30 23:16 ` [patch 25/47] x86: Cleanup io_apic Thomas Gleixner
2010-09-30 23:16 ` [patch 26/47] x86: io_apic: Convert startup to new irq_chip function Thomas Gleixner
2010-09-30 23:16 ` Thomas Gleixner
2010-09-30 23:16 ` [patch 27/47] x86: ioapic: Convert mask " Thomas Gleixner
2010-09-30 23:16 ` [patch 28/47] x86: ioapic/hpet: Convert to new chip functions Thomas Gleixner
2010-09-30 23:16 ` Thomas Gleixner
2010-09-30 23:16 ` [patch 29/47] pci: Convert msi to new irq_chip functions Thomas Gleixner
2010-09-30 23:16 ` Thomas Gleixner
2010-10-11 17:09 ` Jesse Barnes
2010-10-11 17:09 ` Jesse Barnes
2010-09-30 23:16 ` [patch 30/47] dmar: Convert to new irq chip functions Thomas Gleixner
2010-09-30 23:17 ` [patch 31/47] ht: Convert to new irq_chip functions Thomas Gleixner
2010-09-30 23:17 ` Thomas Gleixner
2010-09-30 23:17 ` [patch 32/47] x86: ioapic: Clean up the direct access to irq_desc Thomas Gleixner
2010-09-30 23:17 ` Thomas Gleixner
2010-09-30 23:17 ` [patch 33/47] pci: Cleanup the irq_desc mess in msi Thomas Gleixner
2010-10-11 17:08 ` Jesse Barnes
2010-10-11 17:08 ` Jesse Barnes
2010-09-30 23:17 ` [patch 34/47] x86: ioapic: Convert irq affinity to new chip functions Thomas Gleixner
2010-09-30 23:17 ` [patch 35/47] x86: ioapic: Cleanup some more Thomas Gleixner
2010-09-30 23:17 ` [patch 36/47] x86: ioapic: Cleanup sparse irq code Thomas Gleixner
2010-09-30 23:17 ` Thomas Gleixner
2010-09-30 23:17 ` [patch 37/47] x86: uv: Clean up the direct access to irq_desc Thomas Gleixner
2010-09-30 23:17 ` [patch 38/47] x86: Use sane enumeration Thomas Gleixner
2010-09-30 23:17 ` [patch 39/47] genirq: Remove arch_init_chip_data() Thomas Gleixner
2010-09-30 23:17 ` [patch 40/47] genirq: Sanitize dynamic irq handling Thomas Gleixner
2010-09-30 23:17 ` Thomas Gleixner
2010-10-01 5:47 ` Yinghai Lu
2010-09-30 23:18 ` [patch 41/47] arm: davinci: Cleanup irq_desc access Thomas Gleixner
2010-09-30 23:18 ` Thomas Gleixner
2010-09-30 23:18 ` [patch 42/47] genirq: Remove the now unused sparse irq leftovers Thomas Gleixner
2010-09-30 23:18 ` Thomas Gleixner
2010-09-30 23:18 ` [patch 43/47] x86: xen: Sanitise sparse_irq handling Thomas Gleixner
2010-09-30 23:18 ` Thomas Gleixner
2010-09-30 23:18 ` [patch 44/47] sh: Sanitize sparse irq Thomas Gleixner
2010-09-30 23:18 ` [patch 45/47] x86: lguest: Use new irq allocator Thomas Gleixner
2010-09-30 23:18 ` Thomas Gleixner
2010-09-30 23:18 ` [patch 46/47] powerpc: " Thomas Gleixner
2010-09-30 23:18 ` Thomas Gleixner
2010-10-01 0:42 ` Benjamin Herrenschmidt
2010-10-01 13:07 ` Thomas Gleixner
2010-10-01 20:46 ` Benjamin Herrenschmidt
2010-10-01 21:11 ` Grant Likely
2010-10-01 21:17 ` Benjamin Herrenschmidt
2010-10-03 16:53 ` Eric W. Biederman
2010-10-03 16:53 ` Eric W. Biederman
2010-10-03 18:34 ` Thomas Gleixner
2010-10-03 20:04 ` Thomas Gleixner
2010-10-03 22:54 ` Benjamin Herrenschmidt
2010-10-03 22:54 ` Benjamin Herrenschmidt
2010-10-04 0:15 ` Eric W. Biederman
2010-10-04 0:37 ` Benjamin Herrenschmidt
2010-10-04 16:46 ` Grant Likely [this message]
2010-09-30 23:18 ` [patch 47/47] genirq: Remove the old sparse irq allocator function Thomas Gleixner
2010-09-30 23:18 ` Thomas Gleixner
2010-10-01 3:32 ` [patch 00/47] Sparse irq rework Linus Torvalds
2010-10-01 3:32 ` Linus Torvalds
2010-10-01 5:54 ` Yinghai Lu
2010-10-01 5:54 ` Yinghai Lu
2010-10-01 20:35 ` Thomas Gleixner
2010-10-03 11:23 ` Grant Likely
2010-10-03 11:29 ` Russell King - ARM Linux
2010-10-03 11:29 ` Russell King - ARM Linux
2010-10-03 11:57 ` Grant Likely
2010-10-03 13:48 ` Thomas Gleixner
2010-10-05 10:22 ` Thomas Gleixner
2010-10-05 10:22 ` Thomas Gleixner
2010-10-06 22:45 ` Yinghai Lu
2010-10-06 22:52 ` Thomas Gleixner
2010-10-06 23:37 ` Yinghai Lu
2010-10-07 0:16 ` Yinghai Lu
2010-10-07 4:01 ` Thomas Gleixner
2010-10-07 4:38 ` Yinghai Lu
2010-10-08 21:50 ` Thomas Gleixner
2010-10-08 21:54 ` Thomas Gleixner
2010-10-09 4:26 ` Yinghai Lu
2010-10-09 5:44 ` Yinghai Lu
2010-10-09 6:34 ` Thomas Gleixner
2010-10-09 7:08 ` Yinghai Lu
2010-10-09 7:08 ` Yinghai Lu
2010-10-09 12:08 ` Thomas Gleixner
2010-10-10 9:32 ` Thomas Gleixner
2010-10-10 9:32 ` Thomas Gleixner
2010-10-10 13:30 ` Anca Emanuel
2010-10-11 2:20 ` Yinghai Lu
2010-10-11 2:20 ` Yinghai Lu
2010-10-11 3:50 ` Yinghai Lu
2010-10-11 3:50 ` Yinghai Lu
2010-10-11 8:16 ` Thomas Gleixner
2010-10-11 11:34 ` Benjamin Herrenschmidt
2010-10-11 16:19 ` Yinghai Lu
2010-10-11 16:19 ` Yinghai Lu
2010-10-09 6:10 ` Thomas Gleixner
2010-10-09 7:03 ` Yinghai Lu
2010-10-09 12:12 ` Thomas Gleixner
2010-10-10 2:32 ` Yinghai Lu
2010-10-10 2:32 ` Yinghai Lu
2010-10-10 5:11 ` Yinghai Lu
2010-10-10 5:11 ` Yinghai Lu
2010-10-10 8:20 ` Thomas Gleixner
2010-10-03 16:41 ` Eric W. Biederman
2010-10-03 16:41 ` Eric W. Biederman
2010-10-03 19:16 ` Thomas Gleixner
2010-10-03 22:57 ` Benjamin Herrenschmidt
2010-10-04 16:31 ` Grant Likely
2010-10-04 0:49 ` Eric W. Biederman
2010-10-04 8:05 ` Thomas Gleixner
2010-10-04 1:13 ` Eric W. Biederman
2010-10-04 1:13 ` Eric W. Biederman
2010-10-04 6:36 ` Ingo Molnar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20101004164600.GB13749@angua.secretlab.ca \
--to=grant.likely@secretlab.ca \
--cc=akpm@linux-foundation.org \
--cc=benh@kernel.crashing.org \
--cc=dwmw2@infradead.org \
--cc=ebiederm@xmission.com \
--cc=jbarnes@virtuousgeek.org \
--cc=lethal@linux-sh.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@arm.linux.org.uk \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=torvalds@osdl.org \
--cc=x86@kernel.org \
--cc=yinghai@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).