Re: blcr 0.8.2 with ubuntu karmic (kernel 2.6.31)

From: Paul H. Hargrove (PHHargrove_at_lbl_dot_gov)
Date: Fri Nov 06 2009 - 16:21:50 PST

  • Next message: Neal Becker: "Re: blcr 0.8.2 with ubuntu karmic (kernel 2.6.31)"
    Alan Woodland wrote:
    > 2009/11/2 Alan Woodland <alan.woodland_at_gmail_dot_com>:
    >   
    >> The attached patch fixes the cause of the missing modules when
    >> building on 2.6.31. It doesn't however appear to be the only problem
    >> when building for 2.6.31, it's now hitting a #error which I haven't
    >> looked at yet.
    >>
    >> For those that are interested 2.6.31 no longer sets $(TOPDIR) in
    >> kbuild invocations, so trying to work out if we're using kbuild based
    >> on that fails. I switched to $(obj), I couldn't think of anything
    >> better to use, but I'm sure there is a more appropriate variable to
    >> use instead.
    >>
    >> When I've had more of a look I might post another patch here to fix
    >> the remaining problems.
    >>     
    >
    > Two problems seem to exist with 2.6.31:
    > - find_task_by_pid_type_ns no longer exists, or isn't visible at all.
    > - find_task_by_pid_ns test passes, with a warning, but dmesg reports
    > find_task_by_pid_ns not found at modprobe time. I think this might be
    > a mistake in the kernel headers, but it's still in System.map, so we
    > can work around this maybe.
    >
    > This is the commit log:
    > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=17f98dcf6010a1cfd25d179fd0ce77d3dc2685c3
    >
    > I'm slightly out of my depth here now, I tried to hack a work around,
    > but didn't succeed yet.
    >
    > Alan
    >   
    W/o trying for myself I can't speculate too deeply on 
    find_task_by_pid_type_ns(), but the git commit log above seems to 
    indicate that some functionality has been removed from the kernel.  I 
    don't yet know how it relates to what BLCR is actually doing w/ 
    find_task_by_pid_type_ns().
    
    The commit log also says 
    "remove the exports for find_task_by_pid_ns...."  So, I suggest that the 
    following addition to BLCR's configure.in may be the right fix for that 
    one (since Alan reports that the symbol is still in System.map):
    
    --- configure.ac        23 Aug 2009 22:58:26 -0000      1.410.2.10
    +++ configure.ac        7 Nov 2009 00:15:14 -0000
    @@ -1225,6 +1225,7 @@ CR_CHECK_KERNEL_CALL([find_task_by_pid_n
     if test -z "${HAVE_FIND_TASK_BY_PID}${HAVE_FIND_TASK_BY_PID_NS}"; then
       CR_BAD_KERNEL([unable to determine how to map pid_nr -> struct task])
     fi
    +CR_FIND_KSYM([find_task_by_pid_ns],[CODE])
     
     CR_CHECK_KERNEL_CALL([find_task_by_pid_type],[#include <linux/sched.h>])
     CR_CHECK_KERNEL_CALL([find_task_by_pid_type_ns],[#include <linux/sched.h>])
    
    
    However, it is also possible that BCLR needs to finally move move to the 
    vpid interfaces.
    
    -Paul
    
    -- 
    Paul H. Hargrove                          PHHargrove_at_lbl_dot_gov
    Future Technologies Group                 Tel: +1-510-495-2352
    HPC Research Department                   Fax: +1-510-486-6900
    Lawrence Berkeley National Laboratory     
    

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