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Date: Sat, 8 Nov 2003 14:03:03 -0500 (EST)
From: Robert Watson <rwatson@freebsd.org>
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To: "Jin Guojun [NCS]" <j_guojun@lbl.gov>
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Subject: Re: 4.9 KLDload error
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On Fri, 7 Nov 2003, Jin Guojun [NCS] wrote:

> A KLD module ncs_time_ctl.ko compiled on both 4.8 and 4.9 hosts can be
> loaded by kldload on any 4.8 machine. But neither .ko files can be
> loaded on a 4.9 machine.  The error is: 
> 
> 4.9 # kldload -v ./ncs_time_ctl.ko
> kldload: can't load ./ncs_time_ctl.ko: Exec format error
> 
> kldload should give more error information on what function it failed to load.
> 
> Is this possible a 4.9 bug in kldload? or does some KLD mechanism has
> been changed in 4.9-RELEASE?  Is there any way to analyze what is wrong
> in the 4.9 LKD system? 

Unfortunately, the UNIX "errno" mechanism isn't very expressive.  However,
the kernel linker will send debugging output to the system console.  Check
dmesg and see if there's more information there.  Typically, this error
will be the result of a failure to link symbols in the module: either due
to a symbol already present, or a missing dependency.  To debug this
further, look at the console output, and also compare the output of "nm" 
on the .ko built on 4.8 and 4.9 to see if its dependencies or exposed
symbols have changed.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Network Associates Laboratories