[Qemu-devel] RE: eepro100.c

[Michal Filka]

Hi,

I did a couple of tests.

1. test
Kernel modules from distribution (kvm-72) & new user space application 
(qemu-system-x86_64 - patched kvm-88)

It seems that it is not working
Possibilities:
1) ru is not ready because of other reason than switching to suspended state
2) patch is not working well
3) anything else ;-)

Conclusion: net card emulation is placed in kernel module, so the test was good 
for nothing ;-)

2. test
Kernel modules and user space application from patched kvm-88
It seems, it works well, but 
1) RNR interrupt is not generated
2) processing is significantly slower (with kvm from my distro I had a speed 
(till suspending and restarting ru unit) round 6000 kB/s now it is round 1000 
kB/s

My conclusion is that there is another change in i82577b emulation which solved 
the problem for me - probably some race condition in rx descriptor processing 
disappeared. Or, due to lower transfer speed (see above), processing of rx 
descripors is done in time, so a descriptor with "S bit" is never processed. Do 
you have another idea?

I'll do other stress tests during the night and send you the results. I'll try 
kvm-88 without the patch too.

Thank you for your time.

Michal Filka

> 
> Stefan Weil schrieb:
> > Jan Kiszka schrieb:
> >> Michal Filka wrote:
> >>> Hi,
> >>>
> >>> I have question on i82557b emulation in kvm.
> >>>
> >>> I have run a proprietary operating system (Pharlap OS) in kvm. Part
> >>> of the job has been porting driver for i8255x. During the job I
> >>> discovered that kvm's emulation doesn't support a RNR interrupt (it
> >>> is disabled in the code).
> >>>
> >>> Why is it disabled? I'm running heavily loaded application and I have
> >>> to poll descriptor list instead of waiting for RNR interrupt.
> >> Best asked on qemu-devel, CC'ing the developer of this device model.
> >>
> >> Jan
> >>
> >
> > Hi,
> >
> > up to now, nobody complained about the missing RNR interrupts.
> > Linux obviously works without them, so I had no reason to
> > implement them.
> >
> > The disabled code parts (function eepro100_rnr_interrupt)
> > can be enabled, but you still need code which calls them
> > at the right places.
> >
> > This should not be very difficult if there is some test case
> > which proves the working RNR interrupt.
> >
> > Regards
> > Stefan
> >
> 
> Hi Michal,
> 
> could you please try the appended patch and tell me whether it works?
> 
> Regards
> Stefan
>