Alasdair on Everything   

Autoconf, Automake and Libtoolized version of bzip2

Autoconf, Automake and libtool are 3 utilities designed to simultaneously help and hinder those of us that have to compile software. They together produce the familiar “./configure ; make ; make install” procedure most of us have used time and time again.

Although these tools are universally hated for being overly complex, slow and hard to use, thankfully most projects use them, because the alternative (usually some shitty Makefile that only works on Linux) is far far far worse.

BZip2 is one of those very simple system utilities we all require, where the author only ships a Makefile. Thankfully a helpful SuSE developer has autoconfized it. So grab a copy of those files into your bzip2-1.0.6 folder, and run autogen.sh

If only someone would do this for libxvid and ffmpeg…

Add comment March 28th, 2011

Lame, nasm, and text relocations (textrels)

Well, this took some debugging.

I’ve filed it all in a nasm bug report. To cut a long story short, if you compile LAME with Nasm 2.09, you’ll end up with TEXTRELs in the resultant libmp3lame.so.

What is a TEXTREL you may ask? Something bad! It stops the code being fully PIC (position independent), which stops the shared object being loaded into memory once and mapped multiple times. But worse, it causes Solaris ld to explode when linking:

gcc -shared -Wl,-h -Wl,libmp3lame.so.0 -o .libs/libmp3lame.so.0.0.0 .libs/VbrTag.o .libs/bitstream.o .libs/encoder.o .libs/fft.o .libs/gain_analysis.o .libs/id3tag.o .libs/lame.o .libs/newmdct.o .libs/presets.o .libs/psymodel.o .libs/quantize.o .libs/quantize_pvt.o .libs/reservoir.o .libs/set_get.o .libs/tables.o .libs/takehiro.o .libs/util.o .libs/vbrquantize.o .libs/version.o .libs/mpglib_interface.o -Wl,-z -Wl,allextract ../libmp3lame/i386/.libs/liblameasmroutines.a ../libmp3lame/vector/.libs/liblamevectorroutines.a ../mpglib/.libs/libmpgdecoder.a -Wl,-z -Wl,defaultextract -lm -lsocket -lnsl -lc -maccumulate-outgoing-args
Text relocation remains referenced
against symbol offset in file
 0x6e ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x75 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x9a ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0xa1 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0xa8 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x12b ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x133 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x1a0 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x1aa ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x1b4 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x1c2 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x24c ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x25d ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
 0x39 ../libmp3lame/i386/.libs/liblameasmroutines.a(fft3dn.o)
 0x56 ../libmp3lame/i386/.libs/liblameasmroutines.a(fft3dn.o)
 0x128 ../libmp3lame/i386/.libs/liblameasmroutines.a(fft3dn.o)
 0x142 ../libmp3lame/i386/.libs/liblameasmroutines.a(fft3dn.o)
 0x26e ../libmp3lame/i386/.libs/liblameasmroutines.a(fft3dn.o)
 0x2b9 ../libmp3lame/i386/.libs/liblameasmroutines.a(fft3dn.o)
 0x2d6 ../libmp3lame/i386/.libs/liblameasmroutines.a(fft3dn.o)
 0x398 ../libmp3lame/i386/.libs/liblameasmroutines.a(fft3dn.o)
 0x4ce ../libmp3lame/i386/.libs/liblameasmroutines.a(fft3dn.o)
 0x2c ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
 0x7a ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
 0x88 ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
 0xc4 ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
 0xd9 ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
 0xe7 ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
 0x1d0 ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
 0x1e4 ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
 0x20b ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
 0x219 ../libmp3lame/i386/.libs/liblameasmroutines.a(fftsse.o)
t1l 0x189 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
largetbl 0xde ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
largetbl 0x105 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
largetbl 0x10f ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
table23 0x245 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
table56 0x256 ../libmp3lame/i386/.libs/liblameasmroutines.a(choose_table.o)
ld: fatal: relocations remain against allocatable but non-writable sections
collect2: ld returned 1 exit status

The way to fix the problem is to use NASM 2.08 or earlier, or wait until the bug gets fixed (although they might point their finger at LAME). I’m going to try yasm instead of nasm and see if that works, as an alternative.

If you don’t care about TEXTRELs, on Linux you don’t have to do anything (GNU ld allows them by default), but on Solaris you can tell the Solaris linker to allow impure text segments by adding "-mimpure-text -lrt" to your LDFLAGS. Or, you can use the GNU linker. This is quite hard, but I wrote a blog post about it.

Add comment March 26th, 2011

Using the GNU ld Linker on Solaris

On Solaris, GCC by default is compiled with the option –with-ld=/usr/ccs/bin/ld, telling it to use the Solaris linker. Unfortunately GCC uses this value above all else, meaning it will ignore LD= environment variables to set an alternative linker, such as /usr/sfw/bin/gld

Although tools like libtool/autoconf will pick up your LD= environment variable, and detect which options the linker supports (and whether its GNU ld or not), libtool unfortunately still calls gcc for the linking stage, which then ignores LD=. This makes it near-impossible to use GNU ld without actually doing a nasty hack, like “mv /usr/ccs/bin/ld /usr/ccs/bin/ld.off ; ln -s /usr/sfw/bin/ld /usr/ccs/bin/ld”. Yuck!

However, today when trying to get lame to compile using nasm (which generates objects that refuse to link with Solaris LD), I found Solaris LD accepts a very useful environment variable. The variable is LD_ALTEXEC.

Solaris LD will actually re-exec the value of LD_ALTEXEC, meaning that if you set LD_ALTEXEC to /usr/sfw/bin/gld, when /usr/ccs/bin/ld gets called, it immediately instead calls /usr/sfw/bin/gld with the arguments passed on. Thus, you can use whatever linker you wish. Hurrah! :-)

5 comments March 25th, 2011