[gentoo-user] CFLAGS changes
Hello, Current CFLAGS=-O2 -march=i686 -pipe I want to add -fomit-frame-pointer to my CFLAGS on an existing system that has been running for months. Is this safe or do I have to rebuild everything with somelike emerge -e ? Should it be avoided completely? James -- gentoo-user@lists.gentoo.org mailing list
Re: [gentoo-user] CFLAGS changes
Hello On Thu, Feb 21, 2008 at 01:53:56PM +, James wrote: Current CFLAGS=-O2 -march=i686 -pipe I want to add -fomit-frame-pointer to my CFLAGS on an existing system that has been running for months. Vim syntax highlighting does not show it in red, so I guess it means it is considered generally safe. I seldom recompile the whole system (actually, I did it once only, for split-debug install-sources make effect) and never get much problems. Usually revdep-rebuild solves them all. However, the new flag will be used only in newly compiled packages, so you might have a reason for the rebuild. At the last note, I noticed a use flag for glibc about omit frame pointer, so you might want to turn that on. -- This email has been checked by an automatic damage possibility check system. It can contain harmful instructions if read backwards. Internal checker ID: lacol.cr/cte/ tlah ohce Michal 'vorner' Vaner -- gentoo-user@lists.gentoo.org mailing list
Re: [gentoo-user] CFLAGS changes
James wrote: Hello, Current CFLAGS=-O2 -march=i686 -pipe I want to add -fomit-frame-pointer to my CFLAGS on an existing system that has been running for months. Is this safe or do I have to rebuild everything with somelike emerge -e ? Should it be avoided completely? James Not sure if the flag is safe but I don't think portage will pick up on changes to CFLAGS. You will have to do a emerge -e for all the packages to be compiled with the new setting. You could also just change it and let the packages update over time as they get upgraded. I don't think that will cause any problems. You can also look here: http://www.gentoo.org/doc/en/gcc-optimization.xml Also note, there is a page somewhere that gives the best CFLAGs but I can't find it. Still looking tho. Dale :-) :-) :-) -- gentoo-user@lists.gentoo.org mailing list
Re: [gentoo-user] CFLAGS changes
Dale wrote: James wrote: Hello, Current CFLAGS=-O2 -march=i686 -pipe I want to add -fomit-frame-pointer to my CFLAGS on an existing system that has been running for months. Is this safe or do I have to rebuild everything with somelike emerge -e ? Should it be avoided completely? James Not sure if the flag is safe but I don't think portage will pick up on changes to CFLAGS. You will have to do a emerge -e for all the packages to be compiled with the new setting. You could also just change it and let the packages update over time as they get upgraded. I don't think that will cause any problems. You can also look here: http://www.gentoo.org/doc/en/gcc-optimization.xml Also note, there is a page somewhere that gives the best CFLAGs but I can't find it. Still looking tho. Dale :-) :-) :-) I found it. This is not the official Gentoo site so use your own judgment or ask here before changing the settings. http://gentoo-wiki.com/Safe_Cflags Hope that helps. Dale :-) :-) :-) -- gentoo-user@lists.gentoo.org mailing list
Re: [gentoo-user] CFLAGS changes
On Thursday 21 February 2008, James wrote: Hello, Current CFLAGS=-O2 -march=i686 -pipe I want to add -fomit-frame-pointer to my CFLAGS on an existing system that has been running for months. Is this safe or do I have to rebuild everything with somelike emerge -e ? It's safe. Of course, it takes effect only on newly compiled packages. I think the build systems of most packes set it anyway. Uwe -- Informal Linux Group Namibia: http://www.linux.org.na/ SysEx (Pty) Ltd.: http://www.SysEx.com.na/ -- gentoo-user@lists.gentoo.org mailing list
Re: [gentoo-user] CFLAGS changes
James wrote: Hello, Current CFLAGS=-O2 -march=i686 -pipe I want to add -fomit-frame-pointer to my CFLAGS on an existing system that has been running for months. Is this safe or do I have to rebuild everything with somelike emerge -e ? Should it be avoided completely? James Hi, I am not too good in English but I alway understood that: |-fomit-frame-pointer| Don't keep the frame pointer in a register for functions that don't need one. This avoids the instructions to save, set up and restore frame pointers; it also makes an extra register available in many functions. *It also makes debugging impossible on some machines.* On some machines, such as the VAX, this flag has no effect, because the standard calling sequence automatically handles the frame pointer and nothing is saved by pretending it doesn't exist. The machine-description macro |FRAME_POINTER_REQUIRED| controls whether a target machine supports this flag. See Register Usage http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gccint/Registers.html#Registers. Enabled at levels -O, -O2, -O3, -Os. means, that fomit-frame-pointer is already active when -o ... is choose. see http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Optimize-Options.html#Optimize-Options -- gentoo-user@lists.gentoo.org mailing list
Re: [gentoo-user] CFLAGS changes
On Thu, 21 Feb 2008 13:53:56 + (UTC), James [EMAIL PROTECTED] wrote: Hello, Current CFLAGS=-O2 -march=i686 -pipe I want to add -fomit-frame-pointer to my CFLAGS on an existing system that has been running for months. Is this safe or do I have to rebuild everything with somelike emerge -e ? Should it be avoided completely? James -- gentoo-user@lists.gentoo.org mailing list Compile glibc with USE=glibc-omitfp to use -fomit-frame-pointer more extensively. Question: Why are you using -march=i686 and some more optimized one? Which processor (type and family) so you have? -- gentoo-user@lists.gentoo.org mailing list
Re: [gentoo-user] CFLAGS changes
On Donnerstag, 21. Februar 2008, KH wrote: James wrote: Hello, Current CFLAGS=-O2 -march=i686 -pipe I want to add -fomit-frame-pointer to my CFLAGS on an existing system that has been running for months. Is this safe or do I have to rebuild everything with somelike emerge -e ? Should it be avoided completely? James Hi, I am not too good in English but I alway understood that: |-fomit-frame-pointer| Don't keep the frame pointer in a register for functions that don't need one. This avoids the instructions to save, set up and restore frame pointers; it also makes an extra register available in many functions. *It also makes debugging impossible on some machines.* On some machines, such as the VAX, this flag has no effect, because the standard calling sequence automatically handles the frame pointer and nothing is saved by pretending it doesn't exist. The machine-description macro |FRAME_POINTER_REQUIRED| controls whether a target machine supports this flag. See Register Usage http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gccint/Registers.html#Registers. Enabled at levels -O, -O2, -O3, -Os. means, that fomit-frame-pointer is already active when -o ... is choose. see http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Optimize-Options.html#Optimize- Options man gcc: -O also turns on -fomit-frame-pointer on machines where doing so does not interfere with debugging. It doesn't hurt to set it anyway. If it is enabled by OX, it will be ignored. -- gentoo-user@lists.gentoo.org mailing list
