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Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables"
From: |
Christopher Covington |
Subject: |
Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables" |
Date: |
Wed, 04 Feb 2015 10:55:41 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:33.0) Gecko/20100101 Thunderbird/33.0 |
Hi Gabriel,
Summary up top, why I like the approach below.
On 02/03/2015 02:09 PM, Gabriel L. Somlo wrote:
> Hi,
> For this functionality to really resemble the way environment variables
> are used, environment information should be provided as part of the QEMU
> command line, without the requirement to make a separate/subsequent
> connection to the guest agent. For example:
>
> qemu-system-x86_64 -guest-env="VAR1=value1;VAR2=value 2" -hda image.qcow2
qemu-system-x86_64 -append "myvars=VAR1=value1;VAR2=value2" -hda image.qcow2
> Once the guest is started, it should be possible to query the guest
> environment with something like:
>
> $ qemu-guest-env get VAR1
> value1
>
> $ qemu-guest-env get VAR2
> value 2
eval `sed -nr 's/myvars=(.*)/\1/' /proc/cmdline`
echo $VAR1
echo $VAR2
I have two use cases that I've enabled or would like to enable across a
variety of platforms and architectures:
A) Script workload(s) that should run from a regular "cold" boot.
B) On slow systems, script the workload(s) that should be run immediately
following a checkpoint restore ("warm" boot).
Originally I was using the ARM Angel semihosting command line for both A and
B. But that required a JTAG debugger be attached to hardware devices, so I
switched to appending foo=bar strings to /proc/cmdline, which has the
additional benefit of being portable across architectures. Does QEMU's -append
flag for setting and something like `sed -nr 's/myopts=(.*)/\1/'
/proc/cmdline` for getting work for your use case?
I've wondered about something portable across architectures like QMP or
VirtIO-something for the B use case, but that hasn't really progressed beyond
thought experiment.
Chris
--
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
- Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", (continued)
- Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", Gabriel L. Somlo, 2015/02/03
- Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", Michael Roth, 2015/02/03
- Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", Daniel P. Berrange, 2015/02/04
- Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", Gabriel L. Somlo, 2015/02/04
- Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", Daniel P. Berrange, 2015/02/04
- Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", Gabriel L. Somlo, 2015/02/04
- Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", Daniel P. Berrange, 2015/02/04
Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", Daniel P. Berrange, 2015/02/04
Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables",
Christopher Covington <=
Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables", Richard W.M. Jones, 2015/02/04