Hi,
ludo@xxxxxxx (Ludovic Courtès) writes:
> Thus, when building GCC, `-B' and `-isystem' flags must be passed so
> that it finds the libc headers, as well as a `-Wl,-dynamic-linker' flag
> to pass the path to the dynamic linker. However, none of the
> environment variables supposedly honored by `configure' seem to suffice
> to propagate these flags through all the GCC build tree and all the
> build stages (currently, NixOS GCC builds circumvent this problems by
> hacking around Makefiles).
>
> What's the recommended way to achieve this?
FWIW, I solved it by passing various environment variables, either at
`configure' time, at `make' time, or both. Namely:
1. I passed `CFLAGS_FOR_BUILD' and `LDFLAGS_FOR_BUILD' with the
relevant `-B', `-isystem' and `-Wl,-dynamic-linker' flags to the
top-level `configure'.
2. I then ran `make' with
make BOOT_LDFLAGS="-B/path/to/libc/lib \
-Wl,-dynamic-linker=/path/to/libc/lib/ld-linux.so.2" \
C_INCLUDE_PATH="$PWD/prev-gcc/include:$PWD/prev-gcc/include-fixed:/path/to/libc/include" \
CPPFLAGS="-DSSIZE_MAX=LONG_MAX"
Not all parts of the build require these flags, but it doesn't hurt
to pass them from the beginning. The `CPPFLAGS' setting works
around the fact that GCC ended up using its own <limits.h> (under
`prev-gcc/include-fixed'), which doesn't define `SSIZE_MAX'.
This is somewhat kludgey and inconvenient, maybe redundant, but I
couldn't find any better way.
One complication is that some environment variables are captured and
substituted by `config.status', while others are only read by makefiles
(and sometimes then captured by a sub-`configure'), making step (2)
above unavoidable.
Thanks,
Ludovic.
