From: Anthony Liguori <anthony@codemonkey.ws>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Alex Williamson <alex.williamson@redhat.com>,
qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] [PATCH RFC] vga: flag vga ram for notifiers
Date: Thu, 31 Mar 2011 14:29:50 -0500 [thread overview]
Message-ID: <4D94D62E.2060206@codemonkey.ws> (raw)
In-Reply-To: <AANLkTi=mfnmrcbezqKZWkns-RiRbBDNyiBpqGBtGO=Jp@mail.gmail.com>
On 03/31/2011 02:18 PM, Peter Maydell wrote:
> On 31 March 2011 20:01, Anthony Liguori<anthony@codemonkey.ws> wrote:
>> VGA is just another device. It happens to be that we treat VGA device
>> memory as something that behaves like ram occassionally but that does not
>> make it RAM.
> So, to ask a dumb question, what does make something RAM?
It's a made up concept that we use to make device performance faster.
Basically, RAM should include all of the memory that a reasonable device
(that we control) would DMA to and has a relatively stable mapping.
> My take on RAM is that RAM is just another device; the only
> difference is that you want to be able to implement fast
> paths that go straight(ish) to target memory; but that's
> an optimisation detail, not something that makes RAM
> conceptually different from other devices...
Right, the trouble is, if you want to treat RAM like any other device,
you can't get stable mappings to it which is bad for something like
vhost-net.
Regards,
Anthony Liguori
> -- PMM
>
next prev parent reply other threads:[~2011-03-31 19:29 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-31 17:43 [Qemu-devel] [PATCH RFC] vga: flag vga ram for notifiers Michael S. Tsirkin
2011-03-31 18:33 ` Anthony Liguori
2011-03-31 18:49 ` Michael S. Tsirkin
2011-03-31 19:01 ` Anthony Liguori
2011-03-31 19:07 ` Michael S. Tsirkin
2011-03-31 19:26 ` Anthony Liguori
2011-03-31 20:03 ` Michael S. Tsirkin
2011-03-31 20:21 ` Anthony Liguori
2011-03-31 19:17 ` Alex Williamson
2011-03-31 19:18 ` Peter Maydell
2011-03-31 19:29 ` Anthony Liguori [this message]
2011-03-31 20:12 ` Peter Maydell
2011-03-31 20:23 ` Anthony Liguori
2011-03-31 21:32 ` Peter Maydell
2011-03-31 21:38 ` Michael S. Tsirkin
2011-03-31 21:49 ` Anthony Liguori
2011-03-31 23:42 ` Michael S. Tsirkin
2011-04-01 0:44 ` Anthony Liguori
2011-04-01 1:07 ` Michael S. Tsirkin
2011-04-01 7:12 ` Peter Maydell
2011-04-01 11:21 ` Michael S. Tsirkin
2011-03-31 21:26 ` Michael S. Tsirkin
2011-03-31 21:32 ` Anthony Liguori
2011-03-31 21:37 ` Michael S. Tsirkin
2011-03-31 21:48 ` Anthony Liguori
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4D94D62E.2060206@codemonkey.ws \
--to=anthony@codemonkey.ws \
--cc=alex.williamson@redhat.com \
--cc=mst@redhat.com \
--cc=peter.maydell@linaro.org \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).