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From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>,
	devel@linuxdriverproject.org,
	Haiyang Zhang <haiyangz@microsoft.com>,
	linux-kernel@vger.kernel.org, Dexuan Cui <decui@microsoft.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-api@vger.kernel.org
Subject: Re: [PATCH RFC 1/3] Drivers: hv: kvp: convert userspace/kernel communication to using char device
Date: Fri, 27 Feb 2015 21:27:15 +0100	[thread overview]
Message-ID: <20150227202715.GF2034@potion.brq.redhat.com> (raw)
In-Reply-To: <1425053665-635-2-git-send-email-vkuznets@redhat.com>

2015-02-27 17:14+0100, Vitaly Kuznetsov:
> Re-implement the communication using misc char device. Use ioctl to do
> kernel/userspace version negotiation (doesn't make much sense at this moment
> as we're breaking backwards compatibility but can be used in future).

The main question is whether we want to abolish backward compatibility;
kernel rules are usually against breakages and it's hard to prove that
the bundled daemon is a sole user and gets updated at the same time.
(Note: I'd gladly break anything.)

The ioctl is used too creatively for my liking: as an out-of-band
communication that is required after the main channel has been opened.
It would be simpler to inject the version into first x bytes of the
stream, making a read() after open() mandatory.

(I've only done a high level overview so far.)

  reply	other threads:[~2015-02-27 20:27 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-27 16:14 [PATCH RFC 0/3] Drivers: hv: utils: re-implement the kernel/userspace communication layer Vitaly Kuznetsov
2015-02-27 16:14 ` [PATCH RFC 1/3] Drivers: hv: kvp: convert userspace/kernel communication to using char device Vitaly Kuznetsov
2015-02-27 20:27   ` Radim Krčmář [this message]
2015-03-03  9:53     ` Vitaly Kuznetsov
2015-03-03 19:47       ` Radim Krčmář
2015-02-27 16:14 ` [PATCH RFC 2/3] Drivers: hv: vss: " Vitaly Kuznetsov
2015-02-27 16:14 ` [PATCH RFC 3/3] Drivers: hv: fcopy: make it consistent with vss/kvp Vitaly Kuznetsov
2015-02-27 21:07 ` [PATCH RFC 0/3] Drivers: hv: utils: re-implement the kernel/userspace communication layer Radim Krčmář
2015-03-02 13:33   ` Vitaly Kuznetsov
2015-03-02  2:11 ` KY Srinivasan
2015-03-02 13:37   ` Vitaly Kuznetsov

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