On Thu, Feb 21, 2013 at 12:57:45AM +0200, Damjan Jovanovic wrote: > On Wed, Feb 20, 2013 at 10:51 PM, Tijl Coosemans <t...@coosemans.org> wrote: > > On 20-02-2013 16:48, Konstantin Belousov wrote: > >> On Wed, Feb 20, 2013 at 05:29:01PM +0200, Damjan Jovanovic wrote: > >>> Hi > >>> > >>> Wine needs some of its libraries to be loaded at specific base > >>> addresses (https://wiki.freebsd.org/Wine), something FreeBSD currently > >>> lacks. > >>> > >>> I've written a patch to the dynamic loader (/libexec/ld-elf.so.1) that > >>> loads libraries at their preferred base addresses > >>> (http://www.freebsd.org/cgi/query-pr.cgi?pr=176216), as well as a port > >>> of Prelink to FreeBSD which Wine uses to set base addresses > >>> (http://www.freebsd.org/cgi/query-pr.cgi?pr=176283). Both work :-), > >>> the changed dynamic loader doesn't show any problems in a few days of > >>> testing, and prelink works with the --reloc-only option as used by > >>> Wine. > >>> > >>> Please review/test/comment/commit. > >> > >> Unfortunately, it is not safe. MAP_FIXED overrides any previous mappings > >> which could exist at the specified address. > > > > I've simplified the rtld patch to a single line. The second patch makes > > Wine use -Ttext-segment linker flag instead of prelink. This requires > > binutils from ports, but it's easier than porting prelink. > > > > All of that occurred to me as well. > > The problem with that one-line rtld patch is that loading an > application will now fail if any of its libraries cannot be loaded at > their requested address. But this is intended behaviour. Also, the default virtaddr base for the shared libraries is 0, so the existing binaries should be not affected.
>
> The problem with -Ttext-segment (and isn't it just -Ttext?) is that it
> doesn't seem to work: the base_vaddr seen by rtld will remain 0, and
> the address listed in /proc/.../map is different from what it should
> be. Also run "readelf -l" on a library compiled that way and compare
> with the output of one run through "prelink --reloc-only", you'll see
> the lowest VirtAddr and PhysAddr in LOAD headers change only with
> prelink. I really ported prelink because there was no other choice.
The -Ttext-segment does work. As indicated by Tijl, you need recent
binutils. I just verified that ld 2.32.1 obeys -Ttext-segment.
You can also take a look at the default linker script to see how
-Ttext-segment is used, look for SEGMENT_START("text-segment").
>
> See my attached test cases, and examine the contents of /proc/.../map
> while they run.
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