[Qemu-devel] A number of OSes do not work with kqemu

[Qemu-devel] A number of OSes do not work with kqemu

[Bakul Shah]

The three I am aware of are: openbsd, netbsd & plan9.  They
work fine with -no-kqemu flag.  This is under freebsd but
I believe the same thing happens under linux.

The easiest test case may be plan 9 it seems to dies very
early.  Download the plan9 .iso from one of
    http://www.tip9ug.jp/mirror/plan9.iso.bz2
    http://www.9grid.de/plan9/plan9.iso.bz2

Decompress, fire up qemu and boot from the .iso, giving qemu
some hard disk image.  It will ask whether you want to
install plan9 or boot plan9 from from the CD.  Choose the
latter.  It will die almost right away with an error message
like this:

user fault: addr=00000000 pc=00001020
addr not mapped (vpd=00000000)
pc not mapped (vpd=00000000)
panic: boot process died: sys: trap: fault read addr=0x0 pc=0x00001020

I captured a log with `log all' command to qemu monitor
console and compared the two cases (with and without kqemu).
There are differences in the CCS register like so:

@@ -6489,7 +6489,7 @@
 GDT=     00000000 0000ffff
 IDT=     00000000 0000ffff
 CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
-CCS=00000000 CCD=0000f000 CCO=LOGICB  
+CCS=00000044 CCD=0000f000 CCO=EFLAGS  
 ----------------
 IN: 
 0x000f08e0:  add    $0x4,%sp
@@ -7818,7 +7818,7 @@
 GDT=     00000000 0000ffff
 IDT=     00000000 0000ffff
 CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
-CCS=00000014 CCD=00000400 CCO=EFLAGS  
+CCS=00000000 CCD=00000400 CCO=INCW    
 ----------------
 IN: 
 0x000f9a53:  mov    $0x9fc0,%ax

diff done after filtering out lines matching egrep pattern
"Servicing hardware|kqemu" from both log outputs.

This is about as far as I can get without delving into qemu
and I certainly do not want to reverse engineer kqemu!

-- bakul

Re: [Qemu-devel] A number of OSes do not work with kqemu

[Robert Pangrazio]

Bakul Shah wrote:

>The three I am aware of are: openbsd, netbsd & plan9.  They
>work fine with -no-kqemu flag.  This is under freebsd but
>I believe the same thing happens under linux.
>
>The easiest test case may be plan 9 it seems to dies very
>early.  Download the plan9 .iso from one of
>    http://www.tip9ug.jp/mirror/plan9.iso.bz2
>    http://www.9grid.de/plan9/plan9.iso.bz2
>
>Decompress, fire up qemu and boot from the .iso, giving qemu
>some hard disk image.  It will ask whether you want to
>install plan9 or boot plan9 from from the CD.  Choose the
>latter.  It will die almost right away with an error message
>like this:
>
>user fault: addr=00000000 pc=00001020
>addr not mapped (vpd=00000000)
>pc not mapped (vpd=00000000)
>panic: boot process died: sys: trap: fault read addr=0x0 pc=0x00001020
>
>I captured a log with `log all' command to qemu monitor
>console and compared the two cases (with and without kqemu).
>There are differences in the CCS register like so:
>
>@@ -6489,7 +6489,7 @@
> GDT=     00000000 0000ffff
> IDT=     00000000 0000ffff
> CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
>-CCS=00000000 CCD=0000f000 CCO=LOGICB  
>+CCS=00000044 CCD=0000f000 CCO=EFLAGS  
> ----------------
> IN: 
> 0x000f08e0:  add    $0x4,%sp
>@@ -7818,7 +7818,7 @@
> GDT=     00000000 0000ffff
> IDT=     00000000 0000ffff
> CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
>-CCS=00000014 CCD=00000400 CCO=EFLAGS  
>+CCS=00000000 CCD=00000400 CCO=INCW    
> ----------------
> IN: 
> 0x000f9a53:  mov    $0x9fc0,%ax
>
>diff done after filtering out lines matching egrep pattern
>"Servicing hardware|kqemu" from both log outputs.
>
>This is about as far as I can get without delving into qemu
>and I certainly do not want to reverse engineer kqemu!
>
>-- bakul
>
>
>_______________________________________________
>Qemu-devel mailing list
>Qemu-devel@nongnu.org
>http://lists.nongnu.org/mailman/listinfo/qemu-devel
>
>  
>
I have never tied openbsd, but I have run NetBsd and Plan9(4th edition) 
under Qemu .8.0 with kqemu in windows. You may have to not use kqemu to 
install, i seem to remember doing that.  Once installed though it works 
fine. Also I had to turn hyperthreading off. I have a P4 with 1gb of 
ram. I had allocated 128 for plan 9 and 256 for netbsd. I also remeber 
not having alot of luck running Plan 9 from the CD, even on a real PC. 
It may be a freebsd thing.

Bob

Re: [Qemu-devel] A number of OSes do not work with kqemu

[Bakul Shah]

> I have never tied openbsd, but I have run NetBsd and Plan9(4th edition) 
> under Qemu .8.0 with kqemu in windows. You may have to not use kqemu to 
> install, i seem to remember doing that.  Once installed though it works 
> fine. Also I had to turn hyperthreading off. I have a P4 with 1gb of 
> ram. I had allocated 128 for plan 9 and 256 for netbsd. I also remeber 
> not having alot of luck running Plan 9 from the CD, even on a real PC. 
> It may be a freebsd thing.

It is not clear under what host/osversion kqemu can be used reliably.
See 
    http://m2.dad-answers.com/qemu-forum/viewforum.php?f=16&sid=cc4b0c564718db9b16ef279d73017615
for more reports of kqemu not working.  under FreeBSD.  Also
there was a report on 9fans mailing about kqemu not working
on a ubuntu linux host.  They are not all A bug does not have
to manifest itself everywhere before it gets fixed.  I gaver
a clear repeatable test that works on at least freebsd (but I
suspect also on some linux versions) which should make it
easy to track this down.  Unfortunately I can't do much more
than this not having kqemu sources (which is its authors's
right -- I am just pointing out what I can do under the
circumstance).