[Linux-ia64] Announce: modutils 2.4.24 is available

From: Keith Owens <kaos_at_ocs.com.au>
Date: 2003-03-23 14:16:01
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ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/modutils/v2.4

modutils-2.4.24.tar.gz          Source tarball, includes RPM spec file
modutils-2.4.24-1.src.rpm       As above, in SRPM format
modutils-2.4.24-1.i386.rpm      Compiled with gcc 2.96 20000731,
                                glibc 2.2.2.
modutils-2.4.24-1.ia64.rpm	Compiled with gcc 2.96-ia64-20000731,
				glibc-2.2.3.
patch-modutils-2.4.24.gz        Patch from modutils 2.4.23 to 2.4.24.

Changelog extract

	* Remove the default of exporting all symbols, but only on
	  architectures that have function descriptors (ia64, ppc64).
	* Add libmodutils.a to make clean list.


This version of modutils is functionally identical to 2.4.23 except for
those architectures that have function descriptors, i.e. ia64 and
ppc64.

For historical reasons, insmod and depmod treat modules with neither
EXPORT_SYMBOL() nor EXPORT_NO_SYMBOLS() as exporting everything.  This
provides backwards compatibility with 2.0 kernels and some 2.2 modules.
No new code should be relying on this behaviour and the feature has
been removed in 2.5 kernels.  Unfortunately some developers are still
relying on this default behaviour, even for new code.

When an architecture has function descriptors and uses EXPORT_SYMBOL()
on a function, gcc generates a function descriptor and ksymtab contains
the address of that descriptor.  Without an explicit EXPORT_SYMBOL(),
gcc does not generate a function descriptor and the exported symbol
points to the start of the function body.  Any attempt to call to that
function tries to use the start of the function code as a descriptor
and breaks spectacularly.

To prevent this kernel breakage, I am making an incompatible change to
modutils.  It only affects ia64 and ppc64 users, and only if they are
relying on the deprecated feature of all symbols being exported.

Users on ia64 and ppc64 must ensure that their modules still resolve
and add EXPORT_SYMBOL() where necessary before doing a permanent
upgrade to modutils 2.4.24.  The simplest way to check is to build (but
not install) modutils-2.4.24 then ./depmod/depmod -nae > /dev/null.
Any unresolved references that did not occur with modutils 2.4.23 need
an explicit EXPORT_SYMBOL().  If this is too much bother, stay on
modutils 2.4.23 and risk the kernel breakage.

Other architectures can safely upgrade to 2.4.24 with no change, or
they can stay on 2.4.23.

If anybody fancies a janatorial task, configure modutils 2.4.24 with
CFLAGS="-O2 -Wall -DHAS_FUNCTION_DESCRIPTORS" ./configure, build it
then run ./depmod/depmod -nae > /dev/null.  You can do that on any
architecture to find kernel modules that still rely on exporting all
symbols.

No, I am not going to fudge modutils 2.4 to allow the continued default
export of data symbols but not text symbols on ia64 and ppc64.  It is
too much extra work just to allow the continued use of a deprecated
feature that has already been removed in 2.5 kernels.

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Received on Sat Mar 22 19:16:27 2003

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