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From: Stephen Hemminger <stephen@networkplumber.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Roman Kagan" <rkagan@virtuozzo.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	"Vitaly Kuznetsov" <vkuznets@redhat.com>,
	kvm@vger.kernel.org, "Denis V . Lunev" <den@openvz.org>,
	"Haiyang Zhang" <haiyangz@microsoft.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	"Ingo Molnar" <mingo@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	devel@linuxdriverproject.org,
	"Thomas Gleixner" <tglx@linutronix.de>
Subject: Re: [PATCH 12/15] hyperv: move VMBus connection ids to uapi
Date: Wed, 21 Dec 2016 09:50:49 -0800	[thread overview]
Message-ID: <20161221095049.6fdc3145@xeon-e3> (raw)
In-Reply-To: <20161221154348.GA31401@infradead.org>

On Wed, 21 Dec 2016 07:43:48 -0800
Christoph Hellwig <hch@infradead.org> wrote:

> On Wed, Dec 21, 2016 at 04:39:18PM +0100, Paolo Bonzini wrote:
> > That said, there are precedents in using UAPI this way for PV
> > interfaces.  See for example include/uapi/linux/virtio*.h and
> > arch/x86/include/uapi/asm/kvm_para.h.  
> 
> We have all kinds of historical examples, but most of them turned
> into a major pain sooner or later - my favourite example are the
> SCSI protocol headers.
> 
> Protocols needs to stay compatible on the (virtual) wire, but not
> on the language level.  Locking us into the strict UABI policies
> for them just make someone life horrible further down the road.

If the the protocols come from external sources (like the current NDIS definitions),
then it is not a big deal. There is some overlap already where NDIS is used multiple
places and there are multiple header files with same definition. That could be
fixed.

The bigger problem is that some of the API's between guest and host could be
implemented multiple ways and don't want userspace ABI files constraining how
something like atomic bit operation for wakeup is done.

The other problem with the hyperv headers is they were initially done with
only the Linux driver usage in mind. This made perfect sense at the time,
the problem is that they mix internal state with protocol definitions.

Lastly, there is licensing issues on headers. It would be good to have any
userspace ABI headers licensed with a more liberal license so that BSD and DPDK drivers
could use them directly. Right now each one reinvents.

  parent reply	other threads:[~2016-12-21 17:50 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-20 15:55 [PATCH 00/15] hyperv: more stuff to uapi + cleanup Roman Kagan
2016-12-20 15:55 ` [PATCH 01/15] hyperv: consolidate TSC ref page definitions Roman Kagan
2016-12-20 20:57   ` KY Srinivasan
2016-12-21  6:25     ` Roman Kagan
2016-12-20 15:55 ` [PATCH 02/15] hyperv: uapi-fy synic event flags definitions Roman Kagan
2016-12-20 17:24   ` Stephen Hemminger
2016-12-21  6:33     ` Roman Kagan
2016-12-21 10:58   ` kbuild test robot
2016-12-21 18:58   ` KY Srinivasan
2016-12-20 15:55 ` [PATCH 03/15] hyperv: use standard bitops Roman Kagan
2016-12-21 12:00   ` Olaf Hering
2016-12-21 13:23     ` Roman Kagan
2016-12-22 12:33       ` Paolo Bonzini
2016-12-21 19:08   ` KY Srinivasan
2016-12-20 15:55 ` [PATCH 04/15] hyperv: define VMBus message type Roman Kagan
2016-12-20 15:55 ` [PATCH 05/15] hyperv: GFP_ATOMIC -> GFP_KERNEL Roman Kagan
2016-12-20 15:55 ` [PATCH 06/15] hyperv: avoid unnecessary vmalloc Roman Kagan
2016-12-21 19:19   ` KY Srinivasan
2016-12-20 15:55 ` [PATCH 07/15] hyperv: dedup cpuid definitions Roman Kagan
2016-12-20 15:55 ` [PATCH 08/15] hyperv: dedup crash msr related definitions Roman Kagan
2016-12-20 15:55 ` [PATCH 09/15] hyperv: unify Hyper-V msr definitions Roman Kagan
2016-12-20 15:55 ` [PATCH 10/15] hyperv: uapi-fy PostMessage and SignalEvent hypercall structures Roman Kagan
2016-12-21 19:27   ` KY Srinivasan
2016-12-20 15:55 ` [PATCH 11/15] hyperv: uapi-fy monitored notification structures Roman Kagan
2016-12-20 15:55 ` [PATCH 12/15] hyperv: move VMBus connection ids to uapi Roman Kagan
2016-12-20 17:25   ` Stephen Hemminger
2016-12-21  6:29     ` Roman Kagan
2016-12-21 12:18       ` Christoph Hellwig
2016-12-21 12:59         ` Roman Kagan
2016-12-21 14:26           ` Christoph Hellwig
2016-12-21 14:39             ` Roman Kagan
2016-12-21 15:39             ` Paolo Bonzini
2016-12-21 15:43               ` Christoph Hellwig
2016-12-21 17:25                 ` Paolo Bonzini
2016-12-21 17:50                 ` Stephen Hemminger [this message]
2016-12-21 17:53                   ` Paolo Bonzini
2016-12-21 17:58                   ` Christoph Hellwig
2016-12-21 18:02                     ` Stephen Hemminger
2016-12-21 19:54                       ` KY Srinivasan
2016-12-28 17:09                         ` Roman Kagan
2016-12-29 18:29                           ` Stephen Hemminger
2017-01-02  8:19                           ` Paolo Bonzini
2017-01-09  8:32                             ` Roman Kagan
2017-01-09  8:40                               ` hpa
2017-01-09  8:58                                 ` Roman Kagan
2017-01-09  9:02                                 ` Paolo Bonzini
2017-01-02 19:39                           ` Stephen Hemminger
2017-01-03  9:32                             ` Paolo Bonzini
2016-12-20 15:56 ` [PATCH 13/15] hyperv: move function close to its only callsite Roman Kagan
2016-12-20 15:56 ` [PATCH 14/15] hyperv_vmbus: drop unused definitions Roman Kagan
2016-12-20 15:56 ` [PATCH 15/15] hyperv: redefine hv_message without bitfields Roman Kagan
2016-12-21 18:00 ` [PATCH 00/15] hyperv: more stuff to uapi + cleanup KY Srinivasan
2016-12-28 16:57   ` Roman Kagan
2016-12-30 19:45     ` KY Srinivasan

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