qemu discuss - Jun 2008 - New qemu source drop with improved kqemu module

I have uploaded a current source drop from the qemu subversion repository,
to the download area.  Additionally, there is a new Kernel kqemu module
that will allow a 32-bit guest to run on a 64-bit host.

The current source base uses a different code generator from the orignial
Dyngen one.  The new one is called "TCG" for  "The Code
Generator" and
is supposed to fix the depenedency on gcc-3.x.  This means that gcc4
and studio 11/12 could be used. 

Lastly, I''ve put up instructions on how to compile on OpenSolaris
(OS200805)

There is a known issue with the kqemu module.  Somewhere between 1.0GB
and 1.5GB of ram, a guest may spontaenously panic and abort QEMU.  We
have some smart folks working on it, but so far we have made no progress
on it.

Instructions for Solaris 10/SXCE are found at
http://www.opensolaris.org/os/project/qemu/host/QEMU_On_Solaris10_or_SXCE/

and Instructions for OpenSolaris (OS200805) are found at:
http://www.opensolaris.org/os/project/qemu/host/BuildingOnOS200805/

Links to all the source are in those pages.

Ben
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This message posted from opensolaris.org

On Sun, Jun 22, 2008 at 10:46 PM, Ben Taylor <ben.taylor at sun.com>
wrote:
> I have uploaded a current source drop from the qemu subversion repository,
> to the download area.  Additionally, there is a new Kernel kqemu module
> that will allow a 32-bit guest to run on a 64-bit host.
<snip>

You mentioned memory issues between 1 and 1.5GB of memory. What about
above 1.5GB? Are you saying that you have seen no major issues with
systems that have 4GB or 16GB etc. of memory ?

Dennis

> On Sun, Jun 22, 2008 at 10:46 PM, Ben Taylor <ben.taylor at sun.com>
wrote:
> > I have uploaded a current source drop from the qemu subversion
repository,
> > to the download area.  Additionally, there is a new Kernel kqemu
module
> > that will allow a 32-bit guest to run on a 64-bit host.
> 
> <snip>
> 
> You mentioned memory issues between 1 and 1.5GB of memory. What about
> above 1.5GB? Are you saying that you have seen no major issues with
> systems that have 4GB or 16GB etc. of memory ?

I''ve seen the bug when running a qemu guest with 1.5GB or memory,
on a host that has 8GB of memory.

Running a qemu guest will 1GB memory on the the same 8GB host showed no
guest crashes.

On Mon, Jun 30, 2008 at 12:52 PM, Juergen Keil <jk at tools.de>
wrote:
>
>> On Sun, Jun 22, 2008 at 10:46 PM, Ben Taylor <ben.taylor at
sun.com> wrote:
>> > I have uploaded a current source drop from the qemu subversion
repository,
>> > to the download area.  Additionally, there is a new Kernel kqemu
module
>> > that will allow a 32-bit guest to run on a 64-bit host.
>>
>> <snip>
>>
>> You mentioned memory issues between 1 and 1.5GB of memory. What about
>> above 1.5GB? Are you saying that you have seen no major issues with
>> systems that have 4GB or 16GB etc. of memory ?
>
>
> I''ve seen the bug when running a qemu guest with 1.5GB or memory,
> on a host that has 8GB of memory.
>
> Running a qemu guest will 1GB memory on the the same 8GB host showed no
> guest crashes.
That''s consistent with the behavior I''ve seen also.  using
1.5GB on
a Quad core, 4GB system, the VM reguarly panic''d the guest and
aborted qemu, while at 1GB, I was able to completely boot S10U5
and then patch it.

With any luck, a new member who joined the team may figure out
what is wrong. :-)

Ben

On Mon, Jun 30, 2008 at 4:59 PM, Ben Taylor <bentaylor.solx86 at
gmail.com> wrote:
> On Mon, Jun 30, 2008 at 12:52 PM, Juergen Keil <jk at tools.de>
wrote:
>>
>>> On Sun, Jun 22, 2008 at 10:46 PM, Ben Taylor <ben.taylor at
sun.com> wrote:
>>> > I have uploaded a current source drop from the qemu subversion
repository,
>>> > to the download area.  Additionally, there is a new Kernel
kqemu module
>>> > that will allow a 32-bit guest to run on a 64-bit host.
>>>
>>> <snip>
>>>
>>> You mentioned memory issues between 1 and 1.5GB of memory. What
about
>>> above 1.5GB? Are you saying that you have seen no major issues with
>>> systems that have 4GB or 16GB etc. of memory ?
>>
>>
>> I''ve seen the bug when running a qemu guest with 1.5GB or
memory,
>> on a host that has 8GB of memory.
>>
>> Running a qemu guest will 1GB memory on the the same 8GB host showed no
>> guest crashes.
>
> That''s consistent with the behavior I''ve seen also. 
using 1.5GB on
> a Quad core, 4GB system, the VM reguarly panic''d the guest and
> aborted qemu, while at 1GB, I was able to completely boot S10U5
> and then patch it.
>
> With any luck, a new member who joined the team may figure out
> what is wrong. :-)
I think that you dropped a hint there. Subtle .. but I heard it land
with a thunk.

    :-)

OKay, so I am happy with the 1GB memory limitation for now and perhaps
I can get safety/stability at 1GB. I really do need to get this
working and in a package that can be easily added to Solaris 10 and
*maybe* OpenSolaris too.

Dennis Clarke

I ran into kqemu issues, but normally only on startup.  It turned out that if
ZFS consumed most of available kernel memory, kqemu won''t load because
it can''t allocate its memory image.  The way around this was to cap
ZFS''s cache buffer in /etc/system with zfs:zfs_arc_max.

I''m currently having issues with qemu''s svn trunk and snv95 (
the tarball here works ).   Not sure  what broke.  Qemu with kqemu runs v-e-r-y
slowly (so slow you think it hung), but qemu -no-kqemu works fine.   Was
wondering if anyone has the current trunk work.

-r
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