[hpoj-devel] SMP/2.4 kernel status.

[Burkhard K. <bu...@bu...>]

David Paschal
> 
> ge...@di... said:
> > But when I try to print (or even sometimes when I try "hpo devid") the
> > system locks up.
> >
> > I just obtained a g55, and I am having a problem on a 2.2.17SMP
> > machine.  I  noticed another email that referred to problems like mine
> > on an SMP machine.   I am compiling a non-SMP kernel to see if that is
> > the problem.  I might could  help work through this if it ends being
> > the problem. 
> 
> Hi, Gene and Heath.  Yes, unfortunately the hpoj kernel-mode drivers don't
> work properly with SMP.  Burkhard Kohl and Damcha were working on it,
> and an "smp3.patch.bz2" patch was posted about 10 days ago, but I don't
> know what their current status is.  (Burkhard and Damcha, would you care
> to comment?)  Heath, you're certainly welcome to look into it if you want.
I'll try to summarize the status of our attempts. Unfortunately I do not
have a MP machine and thus can not test SMP issues directly.

The 0.6 driver has problems related to SMP and 2.4.x issues because
it uses non SMP-aware primitives for bottom half locking. Damcha and I
replaced these with their SMP-aware counterparts (which just collapse 
to normal locking primitives for non-SMP systems - will say they work 
as well with non SMP systems). 

We have also addressed the issue of SMP-config awareness by consulting 
the <linux/autoconfig.h> header to decide upon the setting of the
SMP-compiler flags for the hpoj driver modules. Without the patch
the modules were compiled as non-SMP even if the kernel was configured 
for SMP.
Now the modules will get compiled with SMP flags properly depending
on the kernel SMP configuration. If someone wants to override
this setting, he/she has to edit ieee12844/Makefile and uncomment
one of the FORCE_SMP flag settings. (This might be helpful, if you 
don't have the kernel sources or use a precompiled kernel from a 
distribution package).

I further adapted the ieee12844pp module to the new parport interface 
of 2.4.x kernels which should allow for "hotplugging" of parport 
devices.  This feature is not well tested but should work ok with
devices that are already visible when loading the ieee12844<pp> 
modules (the normal situation with board/card based parports).

The new interface allows for 4 MLC links and could easyly be expanded 
for even more links (devices). 

I have the patch tested against a 2.2.14/17 and the 2.4.0-test9 kernel
on my machine. Unfortunately I see an immense slowdown while scanning 
with the 2.4.0 kernel which is not present with 2.2.x. At the moment 
I am trying to isolate that problem (and to include Davids newest patch).

For now I just have one report from Alexander Zimmermann that the patch 
works ok for him on a 2.2.16 SMP kernel with a G85. I'd like to encourage 
everyone with a SMP machine and/or an 2.4.x kernel to test it and 
report success or failure to this list. As I already wrote, I am really
depending on such reports as I don't have SMP hardware.

The patch was posted on Thu, 19 Oct with the subject:
	Patches for 2.4 kernel.
I has to be applied against a clean hpoj-0.6 source tree before
you call ./configure

Burkhard
-- 
Burkhard Kohl			bu...@bu...