linux-kernel - Re: [RFC 0/2] Add Virtual Box vboxguest and vboxsf guest drivers to the mainline kernel

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Message-ID: <f1e1d2ce-3708-d443-6e70-a8c95fdeb71d@redhat.com>
Date:   Fri, 11 Aug 2017 18:09:00 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Michael Thayer <michael.thayer@...cle.com>,
        "Knut St . Osmundsen" <knut.osmundsen@...cle.com>,
        Larry Finger <Larry.Finger@...inger.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>
Subject: Re: [RFC 0/2] Add Virtual Box vboxguest and vboxsf guest drivers to
 the mainline kernel

Hi,

On 11-08-17 18:02, Arnd Bergmann wrote:
> On Fri, Aug 11, 2017 at 3:23 PM, Hans de Goede <hdegoede@...hat.com> wrote:
> 
>> The vboxguest driver introduces a new userspace API + ABI in the form
>> of ioctls on a character device. VirtualBox upstream not willing to
>> commit to keeping this ABI stable was one of the things which has
>> kept this driver driver out of mainline sofar. I've been talking to
>> VirtualBox upstream about mainlining the guest drivers and VirtualBox
>> upstream has agreed to consider the userspace ABI stable and only
>> extend it in a backwards compatible manner.
> 
> Can you clarify which ioctl interface they agreed to? Would they
> only keep the one that the proposed driver implements today,
> or the one we end up with after a full review? ;-)

Given that there are a lot of users already using the existing interface
more the former (the proposed driver implements today) then the latter.

But for now they assume that the userspace and kernel module versions
are always in sync, so some small fixes might be possible. Some questions
from me about unclear behavior of one ioctl command have already let
to one small fix. But in general given the long out of tree history
of this driver the interface is something which will be hard to change.

>> As said this is a RFC, the main comments I'm looking for is an answer
>> to these 2 questions:
>>
>> Greg, Arnd would you be willing to merge the vboxguest driver under
>> drivers/misc (in principle), assuming I do the remaining cleanup
>> and the driver gets a favorable review of course ?
>>
>> Al, the same question for you for the vboxsf (shared folder) driver?
> 
> I think these drivers should be part of the kernel, but I see drivers/misc/
> as a last resort location for things that don't fit anywhere else.

I ended up using drivers/misc because that is where the vmware drivers
are.

> In this case,
> would maybe drivers/platform/vbox or drivers/firmware/vbox be better?

Definitely not drivers/firmware that feels wrong (the driver talks
to a pci device), I personally think adding a new dir under drivers/platform
for just the single driver is overkill.

Regards,

hans