On Sat, Mar 12, 2016 at 3:09 AM, Michael Niedermayer <mich...@niedermayer.cc> wrote: > On Thu, Mar 10, 2016 at 07:57:53PM +0100, Hendrik Leppkes wrote: >> On Mon, Sep 21, 2015 at 6:41 AM, Alex Smith <alex.sm...@warpsharp.info> >> wrote: >> > From: Alex Smith <alex.sm...@warpsharp.info> >> > >> > Binutils will always strip the relocation information from executable >> > files even if it needs it (dynamicbase/ASLR). We can work around this >> > by using the pic-executable flag combined with setting the correct entry >> > point since apparently ld forgets what that should be. This problem >> > affects both 32 and 64-bit mingw-w64. >> > >> > We can combine the nxcompat/dynamicbase check because they were added to >> > binutils at the same time. >> > >> > Signed-off-by: Alex Smith <alex.sm...@warpsharp.info> >> > >> > Conflicts: >> > configure >> > --- >> > configure | 13 +++++++++++-- >> > 1 file changed, 11 insertions(+), 2 deletions(-) >> > >> > diff --git a/configure b/configure >> > index d2a25bb..d6ab35a 100755 >> > --- a/configure >> > +++ b/configure >> > @@ -4367,8 +4367,6 @@ case $target_os in >> > LIBTARGET=arm-wince >> > fi >> > enabled shared && ! enabled small && check_cmd $windres --version >> > && enable gnu_windres >> > - check_ldflags -Wl,--nxcompat >> > - check_ldflags -Wl,--dynamicbase >> > enabled x86_32 && check_ldflags -Wl,--large-address-aware >> > shlibdir_default="$bindir_default" >> > SLIBPREF="" >> > @@ -4392,6 +4390,17 @@ case $target_os in >> > objformat="win32" >> > ranlib=: >> > enable dos_paths >> > + check_ldflags -Wl,--nxcompat,--dynamicbase >> > + # Lets work around some stupidity in binutils. >> > + # ld will strip relocations from executables even though we need >> > them >> > + # for dynamicbase (ASLR). Using -pie does retain the reloc >> > section >> > + # however ld then forgets what the entry point should be (oops) >> > so we >> > + # have to manually (re)set it. >> > + if enabled x86_32; then >> > + add_ldexeflags -Wl,--pic-executable,-e,_mainCRTStartup >> > + elif enabled x86_64; then >> > + add_ldexeflags -Wl,--pic-executable,-e,mainCRTStartup >> > + fi >> > ;; >> > win32|win64) >> > disable symver >> >> This patch (the relocations part) broke debugging mingw-w64 ffmpeg >> builds with gdb, you can't set breakpoints anymore when its applied. >> It should either be reverted or made dependent on >> --enable/disable-debug (I would favor the first, honestly, since its a >> rather ugly hack in itself). > > as i was the one applying it IIRC, i should probably comment ... > iam not against this being partially or fully revered/mode conditional > if it causes more problems than it does good. > >
I was hoping Alex would comment, but not being able to debug using GDB is a serious issue which people have reported ever since it was commited, we just never knew the cause of it. - Hendrik _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
