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Re: [Qemu-devel] Why is SeaBIOS used with -kernel?
From: |
Richard W.M. Jones |
Subject: |
Re: [Qemu-devel] Why is SeaBIOS used with -kernel? |
Date: |
Fri, 1 Apr 2016 19:41:31 +0100 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
On Fri, Apr 01, 2016 at 11:35:40AM -0400, Kevin O'Connor wrote:
> > +# general stuff
> > +CONFIG_QEMU=y
> > +CONFIG_ROM_SIZE=128
>
> Why force a size of 128K - I would think 64K would be fine.
Agreed. Setting this to =0 seems the best thing, and it does fit fine
inside 64K.
> > +# no input, no boot menu
> > +CONFIG_MOUSE=n
> > +CONFIG_KEYBOARD=n
> [...]
> > +CONFIG_DRIVES=n
>
> I would not recommended disabling CONFIG_MOUSE, CONFIG_KEYBOARD,
> CONFIG_DRIVES - I only had those in my config so as to avoid having to
> specify all the device drivers. Ideally these would remain on and the
> individual device drivers would be disabled.
We are always use this in a virtual appliance. Interaction with the
user is both impossible and undesirable. It either boots or not, and
the whole appliance is discarded in seconds. We're always using
-kernel with this SeaBIOS build, so probing drives is never needed.
Below are some benchmarks of the other things you mentioned. These
are complete appliance boot-to-shutdown times [*not* just SeaBIOS].
All debugging has been disabled, and I'm using a slightly different
kernel version, so these runs are not comparable to earlier results I
posted. All times are the mean of 10 runs. The ± number is 1
standard deviation from the mean.
In my estimation only CONFIG_FW_ROMFILE_LOAD=n seems to make a
measurable difference.
----------------------------------------------------------------------
Ordinary qemu SeaBIOS configuration
Result: 1227.5ms ±7.7ms
-bios boot-fast.bin, as per my previous patch
Result: 1113.7ms ±6.4ms
Leaving CONFIG_XEN and CONFIG_THREADS at default settings
Result: 1111.2ms ±3.8ms
CONFIG_USE_SMM=n
Result: 1116.0ms ±5.0ms
CONFIG_FW_ROMFILE_LOAD=n
Result: 1106.6ms ±5.0ms
CONFIG_RELOCATE_INIT=n
Result: 1104.7ms ±11.2ms
----------------------------------------------------------------------
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
libguestfs lets you edit virtual machines. Supports shell scripting,
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- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, (continued)
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin Wolf, 2016/04/05
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/05
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin Wolf, 2016/04/05
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/05
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin Wolf, 2016/04/05
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Gerd Hoffmann, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Paolo Bonzini, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?,
Richard W.M. Jones <=
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Kevin O'Connor, 2016/04/01
- Re: [Qemu-devel] Why is SeaBIOS used with -kernel?, Richard W.M. Jones, 2016/04/02