What should I do for kvm development first?

What should I do for kvm development first?

[Neo Jia]

hi,

I am trying to contribute some (just starting some bug fix first) for
KVM development.

But, I want know first what those experienced kvm developer do
everyday for the development work.

I synced with kvm.git and kvm-userspace.git. Do I have to rebuild and
install the entire kernel every time?

I really appreciate if you can share me your development/debugging
methods for KVM.

Thanks,
Neo
-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

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Re: What should I do for kvm development first?

[Dan Kenigsberg]

On Fri, Nov 16, 2007 at 09:46:03PM -0800, Neo Jia wrote:
> 
> I synced with kvm.git and kvm-userspace.git. Do I have to rebuild and
> install the entire kernel every time?
> 

Luckily, not. By default, when you ./configure in kvm-userspace.git, make
is told to build the kvm kernel module against the currently-running
kernel.

The source code of the kernel module comes from the kvm.git tree. What I
suggest is to
        make -C kernel LINUX=path/to/kvm.git sync
(when in kvm-userspace.git) in order to copy that source code to
kvm-userspace.git.

> I really appreciate if you can share me your development/debugging
> methods for KVM.

I hope you get more clues from other more experienced folks here. Good
luck,

Dan.

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Re: What should I do for kvm development first?

[Izik Eidus]

Dan Kenigsberg wrote:
> On Fri, Nov 16, 2007 at 09:46:03PM -0800, Neo Jia wrote:
>   
>> I synced with kvm.git and kvm-userspace.git. Do I have to rebuild and
>> install the entire kernel every time?
>>
>>     
>
> Luckily, not. By default, when you ./configure in kvm-userspace.git, make
> is told to build the kvm kernel module against the currently-running
> kernel.
>
> The source code of the kernel module comes from the kvm.git tree. What I
> suggest is to
>         make -C kernel LINUX=path/to/kvm.git sync
> (when in kvm-userspace.git) in order to copy that source code to
> kvm-userspace.git.
>
>   
>> I really appreciate if you can share me your development/debugging
>> methods for KVM.
>>     
>
> I hope you get more clues from other more experienced folks here. Good
> luck,
>
> Dan.
>   
development methods:
1)reading the kvm code / reading
2)intel/amd system programming specs
3)ask questions in the list

debugging is very very hard in this area, most of time is just printing 
the values all over kvm
and biesecting.

sometimes you might want to write a test program, but...


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Re: What should I do for kvm development first?

[Neo Jia]

On Nov 17, 2007 7:47 AM, Izik Eidus <izike-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:
>
> Dan Kenigsberg wrote:
> > On Fri, Nov 16, 2007 at 09:46:03PM -0800, Neo Jia wrote:
> >
> >> I synced with kvm.git and kvm-userspace.git. Do I have to rebuild and
> >> install the entire kernel every time?
> >>
> >>
> >
> > Luckily, not. By default, when you ./configure in kvm-userspace.git, make
> > is told to build the kvm kernel module against the currently-running
> > kernel.
> >
> > The source code of the kernel module comes from the kvm.git tree. What I
> > suggest is to
> >         make -C kernel LINUX=path/to/kvm.git sync
> > (when in kvm-userspace.git) in order to copy that source code to
> > kvm-userspace.git.
> >
> >
> >> I really appreciate if you can share me your development/debugging
> >> methods for KVM.
> >>
> >
> > I hope you get more clues from other more experienced folks here. Good
> > luck,
> >
> > Dan.
> >
> development methods:
> 1)reading the kvm code / reading
> 2)intel/amd system programming specs
> 3)ask questions in the list
>
> debugging is very very hard in this area, most of time is just printing
> the values all over kvm
> and biesecting.
>
> sometimes you might want to write a test program, but...

Izik and Dan,

Thank you for your response! Now, I can build modules from kvm.git
instead of build the whole kernel.

Any comments for the TODO item or bug  I need to pick up first?

Thanks,
Neo

>
>



-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

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Re: What should I do for kvm development first?

[Izik Eidus]

On Sat, 2007-11-17 at 23:02 -0800, Neo Jia wrote:
> On Nov 17, 2007 7:47 AM, Izik Eidus <izike-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:
> >
> > Dan Kenigsberg wrote:
> > > On Fri, Nov 16, 2007 at 09:46:03PM -0800, Neo Jia wrote:
> > >
> > >> I synced with kvm.git and kvm-userspace.git. Do I have to rebuild and
> > >> install the entire kernel every time?
> > >>
> > >>
> > >
> > > Luckily, not. By default, when you ./configure in kvm-userspace.git, make
> > > is told to build the kvm kernel module against the currently-running
> > > kernel.
> > >
> > > The source code of the kernel module comes from the kvm.git tree. What I
> > > suggest is to
> > >         make -C kernel LINUX=path/to/kvm.git sync
> > > (when in kvm-userspace.git) in order to copy that source code to
> > > kvm-userspace.git.
> > >
> > >
> > >> I really appreciate if you can share me your development/debugging
> > >> methods for KVM.
> > >>
> > >
> > > I hope you get more clues from other more experienced folks here. Good
> > > luck,
> > >
> > > Dan.
> > >
> > development methods:
> > 1)reading the kvm code / reading
> > 2)intel/amd system programming specs
> > 3)ask questions in the list
> >
> > debugging is very very hard in this area, most of time is just printing
> > the values all over kvm
> > and biesecting.
> >
> > sometimes you might want to write a test program, but...
> 
> Izik and Dan,
> 
> Thank you for your response! Now, I can build modules from kvm.git
> instead of build the whole kernel.
> 
> Any comments for the TODO item or bug  I need to pick up first?
> 
check out:
http://kvm.qumranet.com/kvmwiki/TODO
and:
http://sourceforge.net/tracker/?group_id=180599&atid=893831


> 
> 


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Re: What should I do for kvm development first?

[Avi Kivity]

Neo Jia wrote:
> hi,
>
> I am trying to contribute some (just starting some bug fix first) for
> KVM development.
>
> But, I want know first what those experienced kvm developer do
> everyday for the development work.
>
> I synced with kvm.git and kvm-userspace.git. Do I have to rebuild and
> install the entire kernel every time?
>
> I really appreciate if you can share me your development/debugging
> methods for KVM.
>
>   

I generally compile kvm.git with kvm as modules, and kvm-userspace.git 
with --with-patched-kernel.  If I make a change to kvm, I just recompile 
and reload the modules; no full rebuild is necessary.

Occasionally I merge mainline into kvm.git, which does require a full or 
partial rebuild.


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Re: What should I do for kvm development first?

[Avi Kivity]

Neo Jia wrote:
>
> Thank you for your response! Now, I can build modules from kvm.git
> instead of build the whole kernel.
>
> Any comments for the TODO item or bug  I need to pick up first?
>   

It depends on your knowledge of the x86 architecture and experience in 
virtualization.  If you have little experience, you might try the 
interactivity improvements tasks on the TODO.  If you're looking for a 
difficult task, pick one of the guest failures from the sourceforge bug 
list.

-- 
error compiling committee.c: too many arguments to function


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Re: What should I do for kvm development first?

[Neo Jia]

On Nov 18, 2007 2:47 AM, Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:
> Neo Jia wrote:
> >
> > Thank you for your response! Now, I can build modules from kvm.git
> > instead of build the whole kernel.
> >
> > Any comments for the TODO item or bug  I need to pick up first?
> >
>
> It depends on your knowledge of the x86 architecture and experience in
> virtualization.  If you have little experience, you might try the
> interactivity improvements tasks on the TODO.  If you're looking for a
> difficult task, pick one of the guest failures from the sourceforge bug
> list.
>

Avi,

Thanks for your suggestions! I have some understanding of x86 archs
(tables and system call implementations). For virtualization,  I have
read several papers from vmware.

So, I think probably for me at this moment some simple bugs should be
a good starting point, which can help me understand the code and also
the development/debugging of KVM.

Another question is about the architecture, I found it seems that the
32-bit platform is much more stable than 64-bit. Should I switch my
system to 64-bit for later work?

Thanks,
Neo

>
> --
> error compiling committee.c: too many arguments to function
>
>



-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

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Re: What should I do for kvm development first?

[Avi Kivity]

Neo Jia wrote:
> Another question is about the architecture, I found it seems that the
> 32-bit platform is much more stable than 64-bit. Should I switch my
> system to 64-bit for later work?
>   

Where do you get this impression?  I do almost all of my development on 
64-bit, and I don't recall an issue that was 64-bit host specific.

It is true that 32-bit Windows guests are more mature under kvm that 
64-bit Windows guests.

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error compiling committee.c: too many arguments to function


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Re: What should I do for kvm development first?

[Neo Jia]

On Nov 18, 2007 3:04 AM, Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:
> Neo Jia wrote:
> > Another question is about the architecture, I found it seems that the
> > 32-bit platform is much more stable than 64-bit. Should I switch my
> > system to 64-bit for later work?
> >
>
> Where do you get this impression?  I do almost all of my development on
> 64-bit, and I don't recall an issue that was 64-bit host specific.

Sorry about that ...

because I always saw "host 64-bit" in the bug report although maybe
they are not 64-bit host specific problem.

Neo


>
> It is true that 32-bit Windows guests are more mature under kvm that
> 64-bit Windows guests.
>
> --
>
> error compiling committee.c: too many arguments to function
>
>



-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

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Re: What should I do for kvm development first?

[Avi Kivity]

Neo Jia wrote:
> On Nov 18, 2007 3:04 AM, Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:
>   
>> Neo Jia wrote:
>>     
>>> Another question is about the architecture, I found it seems that the
>>> 32-bit platform is much more stable than 64-bit. Should I switch my
>>> system to 64-bit for later work?
>>>
>>>       
>> Where do you get this impression?  I do almost all of my development on
>> 64-bit, and I don't recall an issue that was 64-bit host specific.
>>     
>
> Sorry about that ...
>
> because I always saw "host 64-bit" in the bug report although maybe
> they are not 64-bit host specific problem.
>   

Yes.  Most testing (and production use) is done on 64-bit hosts, since 
virtualization is memory-intensive.  Also, you can test more types of 
guests this way.  Almost all virtualization-capable processors are also 
64-bit capable.

32-bit hosts are mostly useful for laptop/desktop use.

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Re: What should I do for kvm development first?

[Neo Jia]

Avi Kivity wrote:
> Neo Jia wrote:
>> On Nov 18, 2007 3:04 AM, Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:
>>  
>>> Neo Jia wrote:
>>>    
>>>> Another question is about the architecture, I found it seems that the
>>>> 32-bit platform is much more stable than 64-bit. Should I switch my
>>>> system to 64-bit for later work?
>>>>
>>>>       
>>> Where do you get this impression?  I do almost all of my development on
>>> 64-bit, and I don't recall an issue that was 64-bit host specific.
>>>     
>>
>> Sorry about that ...
>>
>> because I always saw "host 64-bit" in the bug report although maybe
>> they are not 64-bit host specific problem.
>>   
>
> Yes.  Most testing (and production use) is done on 64-bit hosts, since 
> virtualization is memory-intensive.  Also, you can test more types of 
> guests this way.  Almost all virtualization-capable processors are 
> also 64-bit capable.
So, does that mean I need to install a 64-bit host to make the reproduce 
easier?

Neo
>
> 32-bit hosts are mostly useful for laptop/desktop use.
>


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Re: What should I do for kvm development first?

[Avi Kivity]

Neo Jia wrote:
>>>>
>>>>> Another question is about the architecture, I found it seems that the
>>>>> 32-bit platform is much more stable than 64-bit. Should I switch my
>>>>> system to 64-bit for later work?
>>>>>
>>>>>       
>>>>>           
>>>> Where do you get this impression?  I do almost all of my development on
>>>> 64-bit, and I don't recall an issue that was 64-bit host specific.
>>>>     
>>>>         
>>> Sorry about that ...
>>>
>>> because I always saw "host 64-bit" in the bug report although maybe
>>> they are not 64-bit host specific problem.
>>>   
>>>       
>> Yes.  Most testing (and production use) is done on 64-bit hosts, since 
>> virtualization is memory-intensive.  Also, you can test more types of 
>> guests this way.  Almost all virtualization-capable processors are 
>> also 64-bit capable.
>>     
> So, does that mean I need to install a 64-bit host to make the reproduce 
> easier?
>   

A 32-bit host is fine, if you don't run 64-bit guests.

-- 
Any sufficiently difficult bug is indistinguishable from a feature.


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