From: Jan Kiszka <jan.kiszka@web.de>
To: Arthur Chunqi Li <yzt356@gmail.com>
Cc: kvm <kvm@vger.kernel.org>
Subject: Re: How to disable IDE DMA in KVM or in guest OS
Date: Thu, 15 May 2014 08:58:04 +0200 [thread overview]
Message-ID: <5374657C.7030007@web.de> (raw)
In-Reply-To: <CABpY8MJfoEUaJuVqk9SkQuoeodtWp05Qqa-7HuuEyELBb6uKUg@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 963 bytes --]
On 2014-05-15 08:55, Arthur Chunqi Li wrote:
> On Thu, May 15, 2014 at 2:39 PM, Jan Kiszka <jan.kiszka@web.de> wrote:
>> On 2014-05-15 07:54, Arthur Chunqi Li wrote:
>>> Hi Jan and there,
>>>
>>> I want to disable IDE BMDMA in Qemu/KVM and let guest OS uses only PIO
>>> mode. Are there any configurations in Qemu or KVM to disable the
>>> hardware support of DMA?
>>
>> Not that I know. These features are built into the chipsets we emulate,
>> and there seems to be no option to disable them. Maybe the isapc will
>> not expose DMA capabilities - but will also lack a lot of other things
>> like PCI...
>
> Well, if I boot guest Linux with ide-core.nodma=0.0 libata.dma=0
> ide=nodma ide0=nodma, why are bmdma irqs (14 and 15) also triggered? I
> think guest OS should only use PIO in this situation.
To signal data availability e.g.? It's up to the guest driver if it
makes use of asynchronous notifications or polls for this.
Jan
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 263 bytes --]
prev parent reply other threads:[~2014-05-15 6:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-15 5:54 How to disable IDE DMA in KVM or in guest OS Arthur Chunqi Li
2014-05-15 6:39 ` Jan Kiszka
2014-05-15 6:55 ` Arthur Chunqi Li
2014-05-15 6:58 ` Jan Kiszka [this message]
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=5374657C.7030007@web.de \
--to=jan.kiszka@web.de \
--cc=kvm@vger.kernel.org \
--cc=yzt356@gmail.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.