On 5/12/19 1:42 AM, Xi Ruoyao via lfs-dev wrote:
On 2019-05-12 05:24 +0100, Ken Moffat via lfs-dev wrote:
As people probably know, I usually set my own CFLAGS when building
LFS (at a minimum, -O2 to get rid of most debug symbols).
Me too.
But I'm now trying to compare the build times and the size of the
executables for "I did it my way" against using the default CFLAGS
from the individual packages (or from BLFS, or using releease builds
for cmake and meson).
Got through chapter 5 ok, time was not a lot greater but the space
used by /tools was a lot bigger (2.4 GB instead of 851MB). But in
chapter 6 glibc was not happy:
# error "glibc cannot be compiled without optimization"
Looking on google, and trying to follow a link to the FAQ
specifically for this (apparently failed, but left me at hte FAQ)
all I can find is the old advice from Seth: if you use CFLAGS and
the build fails, people will suggest you try without those CFLAGS.
Fine, and I remember suggestions to use -O3 for glibc from Greg
Schafer. So, I've added CFLAGS='-O2' for glibc if my own CFLAGS are
not set (and I had a similar fix which became ineffective when I
reworked how I set/pass my CFLAGS, at that time it was labelled as
being needed for at least x86_32).
But unless I'm looking in the wrong place, I can't see any CFLAGS in
the book ? So, how do you all build glibc in chroot ?
In autotools configure script, if CFLAGS is not set, the script defaults to use
"-O2 -g" or something the package author set. However, if it is set (for some
packages, *even if set to nothing*, i. e. CFLAGS=""), the script will throw away
the default and use your setting.
That's different from cmake or meson. Beside the stupid libtool, I also dislike
this "feature" of autotools.
If you really want to, use CFLAGS='-O0' (Oh zero).
-- Bruce
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