From: Hannes Reinecke <hare@suse.de>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Don Slutz <Don@cloudswitch.com>,
qemu-devel@nongnu.org, Blue Swirl <blauwirbel@gmail.com>,
Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: [Qemu-devel] [PATCH] hw: Add support for new LSI Logic devices.
Date: Thu, 04 Oct 2012 15:45:10 +0200 [thread overview]
Message-ID: <506D92E6.7090504@suse.de> (raw)
In-Reply-To: <50517C05.3080708@redhat.com>
On 09/13/2012 08:24 AM, Paolo Bonzini wrote:
> Il 12/09/2012 15:58, Anthony Liguori ha scritto:
>> Why would someone use this verses megasas vs. LSI vs virtio-scsi?
>
> LSI is dead. Compare it to IDE.
>
> virtio-scsi has the highest performance, but it is not supported on all
> guests. Compare it to virtio-blk.
>
> This vs. megasas is a good question; both can be compared to AHCI, they
> have good performance and have the advantage of compatibility with real
> hardware. If this had gone in first, I would probably have rejected
> megasas, but this has the advantage of being used in VMware and
> VirtualBox. Plus, unlike megasas Don said he'd work on SeaBIOS support,
> so it has further merit.
>
Ah.
Well, I'll be working on SeaBIOS support then, too :-)
I just haven't seen the need yet as it boots happily with an
external ROM ...
However:
The main difference here is that the proposed 'lsilogic' controller
emulates a SCSI or SAS controller, whereas the megasas emulates a
RAID controller.
So for the former you have to implement _lot_ of code to make the
emulation happy; most of which will be static (just look at the
various config pages it'll has to implement) and just adds to the
general size of the code without any functional benefit.
For megasas the controller itself does an emulation, which maps
pretty well to qemu. And you don't have to implement all these
transport-specific details.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
next prev parent reply other threads:[~2012-10-04 13:45 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-11 17:00 [Qemu-devel] [PATCH] hw: Add support for new LSI Logic devices Don Slutz
2012-09-11 23:50 ` Michael S. Tsirkin
2012-09-12 6:01 ` Paolo Bonzini
2012-09-12 12:36 ` Kevin Wolf
2012-09-12 13:58 ` Anthony Liguori
2012-09-13 6:24 ` Paolo Bonzini
2012-09-13 13:14 ` Anthony Liguori
2012-10-04 13:45 ` Hannes Reinecke [this message]
2012-09-13 12:43 ` Don Slutz
2012-09-12 6:58 ` Gerhard Wiesinger
2012-09-13 17:10 ` Don Slutz
2012-09-12 15:38 ` Avi Kivity
2012-09-13 12:46 ` Don Slutz
2012-09-13 13:54 ` Michael S. Tsirkin
2012-09-13 20:57 ` Anthony Liguori
2012-09-29 14:35 ` Don Slutz
2012-10-01 14:25 ` Paolo Bonzini
2012-11-08 19:03 ` Gerhard Wiesinger
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