|Version 2 (modified by 10 years ago) (diff),|
- Frequently asked questions about building GHC
Frequently asked questions about building GHC
This page collects questions and advice about building GHC from source. It is particularly prone to going out of date. Please help keep it relevant and accurate. At the moment it's fairly un-structured; please feel free to add structure if that'd make it easier to follow.
Platform-specific guidance belongs under one of the platform-specific help pages linked from the Building guide contents page.
Space in TMPDIR
One difficulty that comes up from time to time is running out of space
TMPDIR. (It is impossible for the configuration stuff to
compensate for the vagaries of different sysadmin approaches to temp
The quickest way around it is
setenv TMPDIR /usr/tmp or
setenv TMPDIR . (or the equivalent incantation with your shell
The best way around it is to say
build.mk file. Then GHC and the other
tools will use the appropriate directory in all cases.
Warning "warning: assignment from incompatible pointer type"
You may occasionally see a warning from the C compiler when compiling some Haskell code, eg. "warning: assignment from incompatible pointer type". These are usually harmless, but it's a good idea to report it on the mailing list so that we can fix it.
Warning "ar: filename
GlaIOMonad__1_2s.o truncated to
archiving warning messages like the following are not a problem:
ar: filename GlaIOMonad__1_2s.o truncated to GlaIOMonad_ ar: filename GlaIOMonad__2_2s.o truncated to GlaIOMonad_ ...
GCC 4 issues
It has been observed on Gentoo systems that GCC 4 may fail, complaining about there being no
-nopie option. You can either use GCC 3, re-emerge ghc or just edit your
/usr/bin/ghc script to remove the
-nopie flag (the latter is by far the quickest and is perfectly safe).
GHC's sources go through
cpp before being compiled, and
a bit from one Unix to another. One particular gotcha is macro calls
cpps treat the comma inside the string as separating two macro
arguments, so you get
:731: macro `SLIT' used with too many (2) args
cpp doesn't tell you the offending file!
Workaround: don't put weird things in string args to
Cabal/Distribution/Compat/FilePath.hs: No such file or directory
You may see this:
Distribution/Compat/FilePath.hs:2: error: Cabal/Distribution/Compat/FilePath.hs: No such file or directory make: *** [depend] Error 1 make: *** [stage1] Error 1
Be sure you have run
sh darcs-all get to get all necessary packages. Don't forget to run
autoreconf again after you pull in new packages.
xargs: /usr/bin/ar: terminated by signal 11
You may see this when compiling libraries:
(echo Control/Concurrent_stub.o System/CPUTime_hsc.o System/Time_hsc.o ; /usr/bin/find Control/Applicative_split Control/Arrow_split Control/Concurrent_split Control/Concurrent/Chan_split ...long mess... Text/PrettyPrint/HughesPJ_split Text/Printf_split Text/Read_split Text/Read/Lex_split Text/Show_split Text/Show/Functions_split -name '*.o' -print) | xargs /usr/bin/ar q libHSbase.a /usr/bin/ar: creating libHSbase.a xargs: /usr/bin/ar: terminated by signal 11 make: *** [libHSbase.a] Error 125 make: *** Deleting file `libHSbase.a' make: *** [all] Error 1
What is happening is that the ghc build system is linking thousands and
thousands of tiny .o files into
ar isn't optimised for
this use-case and it takes far more memory than it really needs to. So
what happens is that ar takes >500Mb of memory and your virtual
machine / virtual server probably isn't configured with that much memory
and so the linux kernel OOM killer terminates the ar process.
To make this worse, since there are so many .o files, it takes several
invocations of ar to link them all. On each invocation
ar is building
the symbol index (-q is ignored) and this is what takes the most time
and memory. It's a good deal quicker to use a custom program (100 lines
of Haskell) to build
libHSbase.a and then use
ranlib just once to build
the symbol index.
[Duncan Coutts] I submitted a patch to gnu
binutils to make ar take less memory when
linking 1000's of files so it now only takes around 100Mb rather than
500Mb when linking
libHSbase.a. That patch is included in version 2.17 I
think (in other words most systems don't have it yet).
What you can do in the mean time is either configure your virtual
machine with more memory or turn off the split-objs feature when you
configure ghc. Just add
SplitObjs=NO to your
mk/build.mk file (which
may not exist to start with). (The Gentoo ebuild does this