Re: Patch(?): linux-2.4.0-prerelease/drivers/char/drm/Makefile libdrm symbol versioning fix

[Keith Owens <kaos@ocs.com.au>]

On Sun, 31 Dec 2000 21:52:16 -0800, 
"Adam J. Richter" <adam@yggdrasil.com> wrote:
>	There is a thread in linux-kernel about how somewhere in
>linux-2.4.0-test13-preX, the Makefile for drivers/char/drm started
>building libdrm.a and not versioning the symbols.  I believe the
>following patch fixes the problem, but I have not tried it for the
>nonmodular case.
>
>	The change is that libdrm.o is built instead of libdrm.a.  This
>object is linked into the kernel if at least one driver that needs it
>is also linked into the kernel.  Otherwise, it is built as a helper
>module which is automatically loaded by modprobe when a module that
>needs it is loaded.

Having drmlib.o as a helper module will defeat the requirements listed
in drivers/char/drm/Makefile (below).  You end up with one copy of the
library being used by all modules.  See my patch earlier today on l-k
that builds two versions of drmlib.a, for kernel and module.  That
patch preserves the drm requirements.

# libs-objs are included in every module so that radical changes to the
# architecture of the DRM support library can be made at a later time.
#
# The downside is that each module is larger, and a system that uses
# more than one module (i.e., a dual-head system) will use more memory
# (but a system that uses exactly one module will use the same amount of
# memory).
#
# The upside is that if the DRM support library ever becomes insufficient
# for new families of cards, a new library can be implemented for those new
# cards without impacting the drivers for the old cards.  This is significant,
# because testing architectural changes to old cards may be impossible, and
# may delay the implementation of a better architecture.  We've traded slight
# memory waste (in the dual-head case) for greatly improved long-term
# maintainability.

BTW, I disagree with this approach but I guess it is up to the drm
maintainers.

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