From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Date: Sun, 03 Dec 2017 21:22:56 +0000 Subject: Re: Difficulties for compilation without extra optimisation Message-Id: <20171203162256.4ea0750d@vmware.local.home> List-Id: References: <7f072f78-eef4-6d87-d233-cee71dac5a32@users.sourceforge.net> <1512314250.3673.6.camel@primarydata.com> In-Reply-To: <1512314250.3673.6.camel@primarydata.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kernel-janitors@vger.kernel.org On Sun, 3 Dec 2017 15:17:32 +0000 Trond Myklebust wrote: > > I would like to check corresponding build results then without extra > > optimisation applied by the compiler. > > But I got surprised by error messages for a command like the > > following. > > > > elfring@Sonne:~/Projekte/Linux/next-patched> my_cc=/usr/bin/gcc-7 && > > LANG=C make -j4 CC="${my_cc}" HOSTCC="${my_cc}" EXTRA_CFLAGS='-O0' > > allmodconfig fs/nfs/write.o Why would you compile the kernel without optimization? There's many places in the kernel that WILL NOT BUILD without optimization. In fact, we do a lot of tricks to make sure that things work the way we expect it to, because we add broken code that only gets compiled out when gcc optimizes the code the way we expect it to be, and the kernel build will break otherwise. -- Steve