Date: Sat, 28 May 2011 18:23:26 +0000 From: Alexander Best <arundel@freebsd.org> To: Pan Tsu <inyaoo@gmail.com> Cc: freebsd-hackers@FreeBSD.ORG, freebsd-toolchain@FreeBSD.ORG Subject: Re: [rfc] a few kern.mk and bsd.sys.mk related changes Message-ID: <20110528182326.GA75447@freebsd.org> In-Reply-To: <86oc2mlsey.fsf@gmail.com> References: <20110527115147.GA73802@freebsd.org> <3BF63174-1B29-4A4D-96DD-3ED65ED96EAC@bsdimp.com> <20110527181459.GA29908@freebsd.org> <20110527182906.GA31871@freebsd.org> <86oc2mlsey.fsf@gmail.com>
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On Sat May 28 11, Pan Tsu wrote: > Alexander Best <arundel@freebsd.org> writes: > > > On Fri May 27 11, Alexander Best wrote: > >> On Fri May 27 11, Warner Losh wrote: > >> > These look generally good. Just one thing I had a question on: > >> > > >> > # > >> > +# Enable FreeBSD kernel-specific printf format specifiers. Also instruct gcc to > >> > +# enable some diagnostics, which make it easier to pinpoint tinderbox failures. > >> > +CFLAGS+= -fformat-extensions -fdiagnostics-show-option > >> > + > >> > > >> > Does this put sand in the gears of clang support? > > > > i've improved the above comment so as to note that clang won't be affected by > > -fdiagnostics-show-option. the new patch is available here: > > > > http://people.freebsd.org/~arundel/patches/kern.mk-bsy.sys.mk.patch > > > > another "issue" i've come across is the fact that on amd64, -O2 is always being > > set, no matter, if debugging is enabled or disabled. i think amd64 should also > > (just like all the other archs) be using -O, when debugging was enabled. > > Any reason a kernel with symbols (DEBUG) *must* be pessimized to -O1 level? > Looking at r140606 it's not clear how symbols are related to a bump > from -O1 to -O2 for non-amd64 archs. And -RELEASE kernels since at least > 6.0R have `makeoptions DEBUG=-g' uncommented in GENERIC. well i'm not an expert on this. but are we 100% sure that a kernel on amd64 compiled with -O2 frename-registers can be debugged the same way as one with -O? if that is the case: sure...-O2 is fine. ;) however i've often read messages - mostly by bruce evans - claiming that anything greater than -O will in fact decrease a kernel's ability to be debugged just as well as a kernel with -O. cheers. alex > > > changing this is quite easy. so if people think this is something worth > > changing i can integrate it into my existing patch. -- a13x
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