From: "Michael S. Tsirkin" <mst@redhat.com>
To: Igor Mammedov <imammedo@redhat.com>
Cc: "Eduardo Habkost" <ehabkost@redhat.com>,
"Laszlo Ersek" <lersek@redhat.com>,
qemu-devel@nongnu.org, "Gerd Hoffmann" <kraxel@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>,
"Richard Henderson" <rth@twiddle.net>
Subject: Re: [RFC 0/3] acpi: cphp: add CPHP_GET_CPU_ID_CMD command to cpu hotplug MMIO interface
Date: Thu, 10 Oct 2019 14:15:44 -0400 [thread overview]
Message-ID: <20191010140934-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20191010175754.7c62cf8f@Igors-MacBook-Pro>
On Thu, Oct 10, 2019 at 05:57:54PM +0200, Igor Mammedov wrote:
> > Then we should consider switching acpi to use fw cfg.
> > Or build another interface that can scale.
>
> Could be an option, it would be a pain to write a driver in AML for fwcfg access though
> (I've looked at possibility to access fwcfg from AML about a year ago and gave up.
> I'm definitely not volunteering for the second attempt and can't even give an estimate
> it it's viable approach).
>
> But what scaling issue you are talking about, exactly?
Just this: each new thing we add is an ad-hoc data structure with
manually maintained backwards compatibility and no built-in discovery.
fw cfg has built-in discovery and we've finally managed to
handle compatibility reasonably well.
PV is already very problematic. Spreading PV code all over the place
like this is a very bad idea. For you CPU hotplug is something that you
keep in mind first of all, but someone bringing up a new platform
already has a steep hill to climb. Adding tons of custom firmware is
not helping things.
--
MST
next prev parent reply other threads:[~2019-10-10 18:24 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 13:22 [RFC 0/3] acpi: cphp: add CPHP_GET_CPU_ID_CMD command to cpu hotplug MMIO interface Igor Mammedov
2019-10-09 13:22 ` [RFC 1/3] acpi: cpuhp: fix 'Command data' description is spec Igor Mammedov
2019-10-10 12:33 ` Laszlo Ersek
2019-10-17 15:41 ` Igor Mammedov
2019-10-18 13:24 ` Laszlo Ersek
2019-10-10 13:31 ` Laszlo Ersek
2019-10-10 13:36 ` Laszlo Ersek
2019-10-22 17:17 ` Christophe de Dinechin
2019-10-22 17:37 ` Laszlo Ersek
2019-10-09 13:22 ` [RFC 2/3] acpi: cpuhp: add typical usecases into spec Igor Mammedov
2019-10-10 13:04 ` Laszlo Ersek
2019-10-10 13:15 ` Laszlo Ersek
2019-10-10 14:13 ` Laszlo Ersek
2019-10-18 14:45 ` Igor Mammedov
2019-10-09 13:22 ` [RFC 3/3] acpi: cpuhp: add CPHP_GET_CPU_ID_CMD command Igor Mammedov
2019-10-10 14:56 ` Laszlo Ersek
2019-10-10 15:06 ` Michael S. Tsirkin
2019-10-10 17:23 ` Igor Mammedov
2019-10-10 17:53 ` Laszlo Ersek
2019-10-10 19:26 ` Eduardo Habkost
2019-10-11 8:07 ` Laszlo Ersek
2019-10-18 16:18 ` Igor Mammedov
2019-10-21 13:06 ` Laszlo Ersek
2019-10-22 12:39 ` Laszlo Ersek
2019-10-22 14:42 ` Igor Mammedov
2019-10-22 15:49 ` Laszlo Ersek
2019-10-23 14:59 ` Igor Mammedov
2019-10-24 15:07 ` Philippe Mathieu-Daudé
2019-10-10 9:56 ` [RFC 0/3] acpi: cphp: add CPHP_GET_CPU_ID_CMD command to cpu hotplug MMIO interface Michael S. Tsirkin
2019-10-10 13:39 ` Igor Mammedov
2019-10-10 13:59 ` Michael S. Tsirkin
2019-10-10 15:57 ` Igor Mammedov
2019-10-10 18:15 ` Michael S. Tsirkin [this message]
2019-10-11 7:41 ` Laszlo Ersek
2019-10-10 19:20 ` Eduardo Habkost
2019-10-11 8:01 ` Laszlo Ersek
2019-10-11 13:00 ` Michael S. Tsirkin
2019-10-11 16:13 ` Laszlo Ersek
2019-10-11 10:47 ` Igor Mammedov
2019-10-11 6:54 ` Laszlo Ersek
2019-10-10 14:16 ` Eduardo Habkost
2019-10-10 14:49 ` Michael S. Tsirkin
2019-10-10 17:09 ` Igor Mammedov
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