From: Bjorn Helgaas <helgaas@kernel.org>
To: Rui Wang <rui.y.wang@intel.com>
Cc: tglx@linutronix.de, rjw@rjwysocki.net, tony.luck@intel.com,
bhelgaas@google.com, linux-acpi@vger.kernel.org,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot
Date: Wed, 22 Jun 2016 09:53:54 -0500 [thread overview]
Message-ID: <20160622145354.GA25485@localhost> (raw)
In-Reply-To: <1466579612-20417-1-git-send-email-rui.y.wang@intel.com>
On Wed, Jun 22, 2016 at 03:13:32PM +0800, Rui Wang wrote:
> On Friday, June 17, 2016 1:10 AM, Bjorn Helgaas wrote:
> > ioapic_insert_resources() is x86-specific, but I'm not sure why; it seems
> > like it does things that should be applicable to ia64 as well.
> >
> > acpi_ioapic_add() is not x86-specific, and it is called from
> > acpi_pci_root_add() for the hot-add case. You're adding an x86-xpecific call
> > in pci_assign_unassigned_resources(). Why should the hot-add case be for
> > all arches, but the boot-time case only for x86?
>
> Hi Bjorn,
>
> It turns out that IOAPIC hotplug has not been pursued on ia64. There were
> demos showing CPU sockets online/offline on ia64 but the CPUs had no IIO,
> thus no IOAPIC hotplug.
That doesn't mean we need to write code that's gratuitously x86-specific.
> So to answer the first question:
> ioapic_insert_resources() is x86-specific because it's inserting what has
> been setup in io_apic_init_mappings() which, through mpc_ioapic_addr(), is
> capable of handling both the static case (acpi_parse_ioapic(), etc.) and the
> hotplug case (acpi_ioapic_add()). But on ia64, there's only the static
> case through acpi_parse_iosapic(), no need for the hotplug case yet.
ioapic_insert_resources() inserts IOAPIC resources on x86. Where are
IOSAPIC resources inserted on ia64?
> To answer the second question:
> acpi_ioapic_add() is in effect x86-specific, because it's an empty function
> when CONFIG_ACPI_HOTPLUG_IOAPIC isn't defined. And CONFIG_ACPI_HOTPLUG_IOAPIC
> depends on CONFIG_X86_IO_APIC (see drivers/acpi/Kconfig). This was introduced
> in c183619b6 (x86/irq, ACPI: Implement ACPI driver to support IOAPIC hotplug).
> That commit shows the dependency.
>
> I'll send a newer version with comments explaining these.
I'd rather have code that is not x86-specific than comments explaining why
the code is x86-specific.
next prev parent reply other threads:[~2016-06-22 15:10 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-08 6:59 [PATCH V2 0/3] ioapic hot-removal bugs Rui Wang
2016-06-08 6:59 ` [PATCH V2 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot Rui Wang
2016-06-08 8:05 ` kbuild test robot
2016-06-08 9:32 ` [PATCH V3 " Rui Wang
2016-06-10 12:57 ` Thomas Gleixner
2016-06-10 13:56 ` Rafael J. Wysocki
2016-06-10 16:43 ` Bjorn Helgaas
2016-06-12 6:06 ` Rui Wang
2016-06-16 17:09 ` Bjorn Helgaas
2016-06-22 7:13 ` Rui Wang
2016-06-22 14:53 ` Bjorn Helgaas [this message]
2016-06-24 15:18 ` Rui Wang
2016-06-22 7:40 ` [PATCH V4 " Rui Wang
2016-06-22 15:14 ` Bjorn Helgaas
2016-06-23 5:11 `
2016-06-23 17:34 ` Bjorn Helgaas
2016-06-24 15:30 ` Rui Wang
2016-06-26 3:44 ` [PATCH V5 " Rui Wang
2016-08-08 20:22 ` Bjorn Helgaas
2016-08-09 3:23 ` Rui Wang
2016-08-09 12:09 ` Rafael J. Wysocki
2016-06-08 6:59 ` [PATCH V2 2/3] x86/ioapic: Fix wrong pointers in ioapic_setup_resources() Rui Wang
2016-06-10 9:45 ` [tip:x86/urgent] " tip-bot for Rui Wang
2016-06-10 12:01 ` [tip:x86/apic] x86/ioapic: Fix incorrect " tip-bot for Rui Wang
2016-06-10 12:48 ` [tip:x86/urgent] " tip-bot for Rui Wang
2016-06-08 6:59 ` [PATCH V2 3/3] x86/ioapic: Simplify ioapic_setup_resources() Rui Wang
2016-06-10 9:48 ` [tip:x86/apic] " tip-bot for Rui Wang
2016-06-10 12:54 ` tip-bot for Rui Wang
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=20160622145354.GA25485@localhost \
--to=helgaas@kernel.org \
--cc=bhelgaas@google.com \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=rjw@rjwysocki.net \
--cc=rui.y.wang@intel.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
/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).