On 01/21/2010 05:05 PM, Anthony Liguori wrote:
On 01/20/2010 07:18 PM, john cooper wrote:
Chris Wright wrote:
* Daniel P. Berrange (berrange@xxxxxxxxxx) wrote:
To be honest all possible naming schemes for '-cpu<name>' are just as
unfriendly as each other. The only user friendly option is '-cpu host'.
IMHO, we should just pick a concise naming scheme& document it. Given
they are all equally unfriendly, the one that has consistency with
vmware
naming seems like a mild winner.
Heh, I completely agree, and was just saying the same thing to John
earlier today. May as well be -cpu {foo,bar,baz} since the meaning for
those command line options must be well-documented in the man page.
I can appreciate the concern of wanting to get this
as "correct" as possible.
This is the root of the trouble. At the qemu layer, we try to focus on
being correct.
Management tools are typically the layer that deals with being "correct".
A good compromise is making things user tunable which means that a
downstream can make "correctness" decisions without forcing those
decisions on upstream.
In this case, the idea would be to introduce a new option, say something
like -cpu-def. The syntax would be:
-cpu-def
name=coreduo,level=10,family=6,model=14,stepping=8,features=+vme+mtrr+clflush+mca+sse3+monitor,xlevel=0x80000008,model_id="Genuine
Intel(R) CPU T2600 @ 2.16GHz"
Which is not that exciting since it just lets you do -cpu coreduo in a
much more complex way. However, if we take advantage of the current
config support, you can have:
[cpu-def]
name=coreduo
level=10
family=6
model=14
stepping=8
features="+vme+mtrr+clflush+mca+sse3.."
model_id="Genuine Intel..."
And that can be stored in a config file. We should then parse
/etc/qemu/target-<targetname>.conf by default. We'll move the current
x86_defs table into this config file and then downstreams/users can
define whatever compatibility classes they want.
With this feature, I'd be inclined to take "correct" compatibility
classes like Nehalem as part of the default qemurc that we install
because it's easily overridden by a user. It then becomes just a
suggestion on our part verses a guarantee.
It should just be a matter of adding qemu_cpudefs_opts to
qemu-config.[ch], taking a new command line that parses the argument via
QemuOpts, then passing the parsed options to a target-specific function
that then builds the table of supported cpus.
Isn't the outcome of John's patches and these configs will be exactly
the same? Since these cpu models won't ever change, there is no reason
why not to hard code them. Adding configs or command lines is a good
idea but it is more friendlier to have basic support to the common cpus.
This is why qemu today offers: -cpu ?
x86 qemu64
x86 phenom
x86 core2duo
x86 kvm64
x86 qemu32
x86 coreduo
x86 486
x86 pentium
x86 pentium2
x86 pentium3
x86 athlon
x86 n270
So bottom line, my point is to have John's base + your configs. We need
to keep also the check verb and the migration support for sending those.
btw: IMO we should deal with this complexity ourselves and save 99.9% of
the users the need to define such models, don't ask this from a java
programmer, he is running on a JVM :-)
Regards,
Anthony Liguori
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