Date: Tue, 31 May 2011 09:57:42 +0000 From: Alexander Best <arundel@freebsd.org> To: Bruce Cran <bruce@cran.org.uk> Cc: freebsd-hackers@FreeBSD.ORG, freebsd-toolchain@FreeBSD.ORG, Pan Tsu <inyaoo@gmail.com> Subject: Re: [rfc] a few kern.mk and bsd.sys.mk related changes Message-ID: <20110531095742.GA99888@freebsd.org> In-Reply-To: <20110528202619.GA27204@muon.cran.org.uk> References: <20110527115147.GA73802@freebsd.org> <3BF63174-1B29-4A4D-96DD-3ED65ED96EAC@bsdimp.com> <20110527181459.GA29908@freebsd.org> <20110527182906.GA31871@freebsd.org> <86oc2mlsey.fsf@gmail.com> <20110528182326.GA75447@freebsd.org> <20110528202619.GA27204@muon.cran.org.uk>
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On Sat May 28 11, Bruce Cran wrote: > On Sat, May 28, 2011 at 06:23:26PM +0000, Alexander Best wrote: > > > > 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. > > > > The critical option when -O2 is used is -fno-omit-frame-pointers, since removing > frame pointers makes debugging impossible (on i386). With -O2 code is moved around and > removed, so debugging is more difficult, but can still provide useful > information. any reason we cannot use -O2 -fno-omit-frame-pointers -fno-strict-aliasing as standard COPTFLAGS with debugging enabled for *all* archs? > > -- > Bruce Cran -- a13x
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