linux-kernel - Re: Use of virtio device IDs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 08 Nov 2007 08:37:14 +0200
From:	Avi Kivity <avi@...ranet.com>
To:	Gregory Haskins <gregory.haskins.ml@...il.com>
CC:	Anthony Liguori <aliguori@...ibm.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Dor Laor <dor.laor@...ranet.com>,
	virtualization@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: Use of virtio device IDs

Gregory Haskins wrote:
>
>> PCI means that you can reuse all of the platform's infrastructure for
>> irq allocation, discovery, device hotplug, and management.
>>     
>
> Its tempting to use, yes.  However, most of that infrastructure is
> completely inappropriate for a PV implementation, IMHO.  

Why?

> You are
> probably better off designing something that is PV specific instead of
> shoehorning it in to fit a different model (at least for the things I
> have in mind).  

Well, if we design our pv devices to look like hardware, they will fit
quite well.  Both to the guest OS and to user's expectations.

> Its not a heck of a lot of code to write a pv-centric
> version of these facilities.
>
>   

It is.  Especially if you consider Windows and a gazillion versions of
deployed, non-pv-capable Linux systems.  For pv-friendly newer Linux,
it's probably doable, but why?

Look at the mess Xen finds itself in.

>> You can write it for new guests but backporting it to older guests will be a
>> huge task.
>>
>> We will support non-pci for s390, but in order to support Windows and
>> older Linux PCI is necessary.
>>     
>
> I don't know if I would agree with "necessary".  "Easier" perhaps. ;) By
> definition once you are PV you are hypervisor aware.  Now its just a
> matter of plugging in the appropriate plumbing to bridge the hypervisor
> to the guest-os.  Some might be easier than others, sure.  But all
> should be extensible to a degree.
>
>   

It's "necessary" in a pragmatic sense: we want to deliver drivers that
provide features for a wide variety of guests in a reasonable
timeframe.  And that means no rewriting guest OS infrastructure.


-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/