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From: rusty@rustcorp.com.au (Rusty Russell)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 0/2] Early printk support for virtio console devices.
Date: Wed, 01 May 2013 11:37:36 +0930	[thread overview]
Message-ID: <87sj27xxjr.fsf@rustcorp.com.au> (raw)
In-Reply-To: <C52CCDD4-D8FB-4AD6-B83D-3B5251A7A0F5@suse.de>

Alexander Graf <agraf@suse.de> writes:
> There are not device specific registers in
> virtio-console. Virtio-console lives behind a virtio bus which doesn't
> know what these registers are.

You're not going to make coherent arguments without reading that actual
patch we're discussing.  And you're going to just waste everyone else's
time.

> Even if you shove it into config space,

Which is what the patch does...

> it'd be broken because config access happens without intercepts on
> some platforms.

But people keep assuming it, which is one reason virtio_ccw switched
from passive lguest-style config to active.  Only lguest and the old kvm
virtio use it, and lguest can change.

An emergency output is a reasonable idea, and this is a reasonable
implementation.  The question is practical: will it be used?  Because we
don't implement reasonable ideas which aren't going to be used.

Cheers,
Rusty.

WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Alexander Graf <agraf@suse.de>,
	Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Cc: "linux-arm-kernel\@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linaro-kernel\@lists.linaro.org"
	<linaro-kernel@lists.linaro.org>,
	"patches\@linaro.org" <patches@linaro.org>,
	"linux-kernel\@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>,
	"kvmarm\@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
	Peter Maydell <peter.maydell@linaro.org>
Subject: Re: [PATCH 0/2] Early printk support for virtio console devices.
Date: Wed, 01 May 2013 11:37:36 +0930	[thread overview]
Message-ID: <87sj27xxjr.fsf@rustcorp.com.au> (raw)
In-Reply-To: <C52CCDD4-D8FB-4AD6-B83D-3B5251A7A0F5@suse.de>

Alexander Graf <agraf@suse.de> writes:
> There are not device specific registers in
> virtio-console. Virtio-console lives behind a virtio bus which doesn't
> know what these registers are.

You're not going to make coherent arguments without reading that actual
patch we're discussing.  And you're going to just waste everyone else's
time.

> Even if you shove it into config space,

Which is what the patch does...

> it'd be broken because config access happens without intercepts on
> some platforms.

But people keep assuming it, which is one reason virtio_ccw switched
from passive lguest-style config to active.  Only lguest and the old kvm
virtio use it, and lguest can change.

An emergency output is a reasonable idea, and this is a reasonable
implementation.  The question is practical: will it be used?  Because we
don't implement reasonable ideas which aren't going to be used.

Cheers,
Rusty.

  reply	other threads:[~2013-05-01  2:07 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-26 11:04 [PATCH 0/2] Early printk support for virtio console devices Pranavkumar Sawargaonkar
2013-04-26 11:04 ` Pranavkumar Sawargaonkar
2013-04-26 11:04 ` [PATCH 1/2] virtio: console: Add early writeonly register to config space Pranavkumar Sawargaonkar
2013-04-26 11:04   ` Pranavkumar Sawargaonkar
2013-04-29  3:10   ` Rusty Russell
2013-04-29  3:10     ` Rusty Russell
2013-04-26 11:04 ` [PATCH 2/2] arm64: earlyprintk support for virtio-mmio console Pranavkumar Sawargaonkar
2013-04-26 11:04   ` Pranavkumar Sawargaonkar
2013-04-26 11:19 ` [PATCH 0/2] Early printk support for virtio console devices Alexander Graf
2013-04-26 11:19   ` Alexander Graf
2013-04-26 11:33   ` Peter Maydell
2013-04-26 11:33     ` Peter Maydell
2013-04-26 12:06     ` Anup Patel
2013-04-26 12:06       ` Anup Patel
2013-04-26 12:33       ` Arnd Bergmann
2013-04-26 12:33         ` Arnd Bergmann
2013-04-26 12:59         ` Anup Patel
2013-04-26 12:59           ` Anup Patel
2013-04-26 15:03           ` Arnd Bergmann
2013-04-26 15:03             ` Arnd Bergmann
2013-04-26 15:54             ` Marc Zyngier
2013-04-26 15:54               ` Marc Zyngier
2013-04-26 15:19         ` Peter Maydell
2013-04-26 15:19           ` Peter Maydell
2013-04-29  3:09   ` Rusty Russell
2013-04-29  3:09     ` Rusty Russell
2013-04-29 12:22     ` Alexander Graf
2013-04-29 12:22       ` Alexander Graf
2013-04-29 12:48       ` Pranavkumar Sawargaonkar
2013-04-29 12:48         ` Pranavkumar Sawargaonkar
2013-04-29 12:53         ` Alexander Graf
2013-04-29 12:53           ` Alexander Graf
2013-05-01  2:07           ` Rusty Russell [this message]
2013-05-01  2:07             ` Rusty Russell
2013-05-01  6:53             ` Anup Patel
2013-05-01  6:53               ` Anup Patel
2013-05-01 14:46               ` Will Deacon
2013-05-01 14:46                 ` Will Deacon
2013-05-02 10:06             ` Peter Maydell
2013-05-02 10:06               ` Peter Maydell
2013-05-06  5:11               ` Rusty Russell
2013-05-06  5:11                 ` Rusty Russell
2013-05-06  9:14                 ` Peter Maydell
2013-05-06  9:14                   ` Peter Maydell
2013-05-07  4:46                   ` Rusty Russell
2013-05-07  4:46                     ` Rusty Russell
2013-05-07 12:19                     ` Peter Maydell
2013-05-07 12:19                       ` Peter Maydell
2013-05-07 15:52                       ` Christopher Covington
2013-05-07 15:52                         ` Christopher Covington
2013-05-07 15:58                         ` Peter Maydell
2013-05-07 15:58                           ` Peter Maydell
2013-05-08 14:17                           ` Catalin Marinas
2013-05-08 14:17                             ` Catalin Marinas
2013-05-09 10:39                             ` Grant Likely
2013-05-09 10:39                               ` Grant Likely
2013-05-06  9:40                 ` Pranavkumar Sawargaonkar
2013-05-06  9:40                   ` Pranavkumar Sawargaonkar
2013-04-29 12:50       ` Peter Maydell
2013-04-29 12:50         ` Peter Maydell
2013-04-29 12:53         ` Alexander Graf
2013-04-29 12:53           ` Alexander Graf
2013-04-30  0:32       ` Rusty Russell
2013-04-30  0:32         ` Rusty Russell
2013-05-01  0:26         ` Alexander Graf
2013-05-01  0:26           ` Alexander Graf
2013-05-01  5:01           ` Anup Patel
2013-05-01  5:01             ` Anup Patel

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