Re: [PATCH 1/3] rt-tests: Support user supplied CFLAGS and LDFLAGS

On 03/21/2012 12:10 PM, Denys Dmytriyenko wrote:

On Tue, Mar 20, 2012 at 05:10:48PM -0700, Darren Hart wrote:

quoted

On 03/20/2012 04:58 PM, John Kacur wrote:

quoted

On Tue, Mar 20, 2012 at 8:05 PM, Darren Hart [off-list ref] wrote:

quoted

Accept user supplied CFLAGS and LDFLAGS, overwriting the
Makefile supplied versions. This can cause the build to
fail if the user does not provide at least what the Makefile
defines, but so be it.

Signed-off-by: Darren Hart <redacted>
CC: Clark Williams <redacted>
CC: John Kacur <jkacur@redhat.com>
CC: Denys Dmytriyenko <redacted>
---

I was just wondering what you need LDFLAGS for? Chatting with Darren
on IRC, it seems like you're using -Wl to pass options via gcc to the
linker, and we don't have loadable libs either. Maybe you could resend
the patch with just the CFLAGS change until we have a real world
reason for LDFLAGS

Denys,

Am I missing a reason why we need LDFLAGS? With the current Makefile. we
could just add anything we want to CFLAGS in a pinch anyway...

Darren,

From OE-Core config files:

LINKER_HASH_STYLE ??= "gnu"
TARGET_LINK_HASH_STYLE ?= "${@['-Wl,--hash-style=gnu',''][d.getVar('LINKER_HASH_STYLE', True) != 'gnu']}"
export TARGET_LDFLAGS = "-Wl,-O1 ${TARGET_LINK_HASH_STYLE}"
ASNEEDED = "-Wl,--as-needed"
TARGET_LDFLAGS += "${ASNEEDED}"
export LDFLAGS = "${TARGET_LDFLAGS}"


So, those are still linker flags (altough passed through -Wl to gcc), hence 
they belong to LDFLAGS, not CFLAGS. Arguably, you only need to pass CFLAGS 
during compile stage and LDFLAGS during link stage. On the other hand, as a 
workaround, I was passing them to TARGET_CC_ARCH, which gets embedded into CC 
and won't distinguish between compile/link stages...

So rt-tests just gets away not using LDFLAGS and re-using CFLAGS for the link 
stage. :) But the current Makefile as it is now won't honor CFLAGS being set 
from outside, unless you pass them explicitly on the command line to make, or 
call make with -e flag.

Right, at the very least I'll resubmit the patch allowing override of
CFLAGS. But I wanted to know if you felt there was any need to support
overriding of LDFLAGS for rt-tests which doesn't build any shared libs.


-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel