Re: [-next] FATAL: drivers/gpu/drm/udl/udl: sizeof(struct usb_device_id)=24 is not a modulo of the size of section __mod_usb_device_table=44.

Andreas Schwab [off-list ref] writes:

Bjørn Mork [off-list ref] writes:

quoted

AFAIK (which admittedly is not much wrt cross building) there is no way
we can make the host built file2alias know the proper aligment for the
structure in the target built modules.  That's the background for this
fix: 

commit 4ce6efed48d736e3384c39ff87bda723e1f8e041
Author: Sam Ravnborg [off-list ref]
Date:   Sun Mar 23 21:38:54 2008 +0100

    kbuild: soften modpost checks when doing cross builds

This is not a fix in any sense of the word.  modpost can only work
properly if its view of the device_id structures matches *exactly* that
of the target.

You are absolutely correct, of course.  I am starting to believe Greg is
correct.  Cross building works mostly by pure luck :-)

I found that the reason the change I referred to above didn't kick in
was because CONFIG_DEBUG_SECTION_MISMATCH was set, causing modpost to be
called from scripts/Makefile.build without the "-c" option:

 # Do section mismatch analysis for each module/built-in.o
 ifdef CONFIG_DEBUG_SECTION_MISMATCH
   cmd_secanalysis = ; scripts/mod/modpost $@
 endif


But as you point out: The whole "soften modpost check" concept is bogus.
It just cannot work.  And I just verified it doing a m68k allmodconfig
build without CONFIG_DEBUG_SECTION_MISMATCH.  modpost will bail out
unless host and target aligment matches:

  scripts/mod/modpost -m -a -o /usr/local/src/build-tmp/linux/Module.symvers    -S  -c -s
drivers/media/video/gspca/gspca_sunplus: struct usb_device_id is 24 bytes.  The last of 55 is:
0x04 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
FATAL: drivers/media/video/gspca/gspca_sunplus: struct usb_device_id is not terminated with a NULL entry!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2


So the prosed fix from Greg is certainly the correct one, until someone
rewrites modpost to be completely cross build safe.


Bjørn
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