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diff --git a/INSTALL/FAQ b/INSTALL/FAQ new file mode 100644 index 00000000000..343243ddb17 --- /dev/null +++ b/INSTALL/FAQ @@ -0,0 +1,322 @@ +egcs Frequently Asked Questions + + +How is egcs be different from gcc2? + +Six years ago, gcc version 1 had reached a point of stability. For the +targets it could support, it worked well. It had limitations inherent in +its design that would be difficult to resolve, so a major effort was made +and gcc version 2 was the result. When we had gcc2 in a useful state, +development efforts on gcc1 stopped and we all concentrated on making +gcc2 better than gcc1 could ever be. This is the kind of step forward +we want to make with egcs. + +In brief, the three biggest differences between egcs and gcc2 are +these: + + + More rexamination of basic architectual decisions of + gcc and an interest in adding new optimizations; + + working with the groups who have fractured out from gcc2 (like + the Linux folks, the Intel optimizations folks, Fortran folks) + including more front-ends; and finally + + An open development model (see below) for the development process. + + +These three differences will work together to result in a more +useful compiler, a more stable compiler, a central compiler that works +for more people, a compiler that generates better code. + + +There are a lot of exciting compiler optimizations that have come +out. We want them in gcc. There are a lot of front ends out there for +gcc for languages like Fortran or Pascal. We want them easily +installable by users. After six years of working on gcc2, we've come +to see problems and limitations in the way gcc is architected; it is +time to address these again. + + +What is an open development model? + +With egcs, we are going to try a bazaar style[1] approach to its +development: We're going to be making snapshots publically available +to anyone who wants to try them; we're going to welcome anyone to join +the development mailing list. All of the discussions on the +development mailing list are available via the web. We're going to be +making releases with a much higher frequency than they have been made +in the past: We're shooting for three by the end of 1997. + +In addition to weekly snapshots of the egcs development sources, we +are going to look at making the sources readable from a CVS server by +anyone. We want to make it so external maintainers of parts of egcs +are able to commit changes to their part of egcs directly into the +sources without going through an intermediary. + +There have been many potential gcc developers who were not able to +participate in gcc development in the past. We these people to help in +any way they can; we ultimately want gcc to be the best compiler in the +world. + +A compiler is a complicated piece of software, there will still be +strong central maintainers who will reject patches, who will demand +documentation of implementations, and who will keep the level of +quality as high as it is today. Code that could use wider testing may +be intergrated--code that is simply ill-conceived won't be. + +egcs is not the first piece of software to use this open development +process; FreeBSD, the Emacs lisp repository, and Linux are a few +examples of the bazaar style of development. + +With egcs, we will be adding new features and optimizations at a +rate that has not been done since the creation of gcc2; these additions +will inevitably have a temporarily destabilizing effect. With the help +of developers working together with this bazaar style development, the +resulting stability and quality levels will be better than we've had +before. + +cathedral-vs-bazaar[1] + We've been discussing different development models a lot over the + past few months. The paper which started all of this introduced two + terms: A cathedral development model versus a bazaar + development model. The paper is written by Eric S. Raymond, it is + called `` http://locke.ccil.org/~esr/writings/cathedral.html" The + Cathedral and the Bazaar''. The paper is a useful starting point + for discussions. + + + +bits/libc-lock.h: No such file or directory +egcs includes a tightly integrated libio and libstdc++ implementation which +can cause problems on hosts which have libio integrated into their C library +(most notably Linux). + +We believe that we've solved the major technical problems for the most +common versions of libc found on Linux systems. However, some versions +of Linux use pre-release versions of glibc2, which egcs has trouble detecting +and correctly handling. + +If you're using one of these pre-release versions of glibc2, you may get +a message "bits/libc-lock.h: No such file or directory" when building egcs. +Unfortunately, to fix this problem you will need to update your C library to +glibc2.0.5c. + +Late breaking news: we may have at least a partial solution for these +problems. So this FAQ entry may no longer be needed. + + +`_IO_stdfile_0_lock' was not declared in this scope +If you get this error, it means either egcs incorrectly guessed what version +of libc is installed on your linux system, or you incorrectly specified a +version of glibc when configuring egcs. + +If you did not provide a target name when configuring egcs, then you've +found a bug which needs to be reported. If you did provide a target name at +configure time, then you should reconfigure without specifying a target name. + + +Problems building the Fortran compiler +The Fortran front end can not be built with most vendor compilers; it must +be built with gcc. As a result, you may get an error if you do not follow +the install instructions carefully. + +In particular, instead of using "make" to build egcs, you should use +"make bootstrap" if you are building a native compiler or "make cross" +if you are building a cross compiler. + +It has also been reported that the Fortran compiler can not be built +on Red Hat 4.X linux for the Alpha. Fixing this may require upgrading +binutils or to Red Hat 5.0; we'll provide more information as it becomes +available. + + +Problems building on MIPS platforms +egcs requires the use of GAS on all versions of Irix, except Irix 6 due +to limitations in older Irix assemblers. + + Either of these messages indicates that you are using the MIPS assembler +when instead you should be using GAS. + + as0: Error: ./libgcc2.c, line 1:Badly delimited numeric literal + .4byte $LECIE1-$LSCIE1 + as0: Error: ./libgcc2.c, line 1:malformed statement + + + + as0: Error: /home/law/egcs_release/gcc/libgcc2.c, line 1:undefined symbol in expression + .word $LECIE1-$LSCIE1 + + + For Irix 6, you should use the native assembler as GAS is not supported +on Irix 6. + + +Problems with exception handling on x86 platforms +If you are using the GNU assembler (aka gas) on an x86 platform and +exception handling is not working correctly, then odds are you're using a +buggy assembler. + +We recommend binutils-2.8.0.1.15 or newer. +"ftp://tsx-11.mit.edu/pub/linux/packages/GCC/binutils-2.8.1.0.15.tar.gz binutils-2.8.0.1.15 source +ftp://tsx-11.mit.edu/pub/linux/packages/GCC/binutils-2.8.1.0.15.bin.tar.gz binutils-2.8.0.1.15 x86 binary for libc5 +ftp://tsx-11.mit.edu/pub/linux/packages/GCC/binutils-2.8.1.0.15.glibc.bin.tar.gz binutils-2.8.0.1.15 x86 binary for glibc2 +Or, you can try a +ftp://ftp.cygnus.com/pub/egcs/infrastructure/gas-970915.tar.gz binutils snapshot; however, be aware that the binutils snapshot is untested +and may not work (or even build). Use it at your own risk. + + +Bootstrap comparison failures on HPs +If you bootstrap the compiler on hpux10 using the HP assembler instead of +gas, every file will fail the comparison test. + +The HP asembler inserts timestamps into object files it creates, causing +every file to be different. The location of the timestamp varies for each +object file, so there's no real way to work around this mis-feature. + +Odds are your compiler is fine, but there's no way to be certain. + +If you use GAS on HPs, then you will not run into this problem because +GAS never inserts timestamps into object files. For this and various other +reasons we highly recommend using GAS on HPs. + + +Bootstrap loops rebuilding cc1 over and over +When building egcs, the build process loops rebuilding cc1 over and +over again. This happens on mips-sgi-irix5.2, and possibly other platforms. + +This is probably a bug somewhere in the egcs Makefile. Until we find and +fix this bug we recommend you use GNU make instead of vendor supplied make +programs. + + +Dynamic linker is unable to find GCC libraries +This problem manifests itself by programs not finding shared libraries +they depend on when the programs are started. Note this problem often manifests +itself with failures in the libio/libstdc++ tests after configuring with +--enable-shared and building egcs. + +GCC does not specify a runpath so that the dynamic linker can find dynamic +libraries at runtime. + +The short explaination is that if you always pass a -R option to the +linker, then your programs become dependent on directories which +may be NFS mounted, and programs may hang unnecessarily when an +NFS server goes down. + +The problem is not programs that do require the directories; those +programs are going to hang no matter what you do. The problem is +programs that do not require the directories. + +SunOS effectively always passed a -R option for every -L option; +this was a bad idea, and so it was removed for Solaris. We should +not recreate it. + + +Unable to run the testsuite +If you get a message about unable to find "standard.exp" when trying to +run the egcs testsuites, then your dejagnu is too old to run the egcs tests. +You will need to get a newer version of dejagnu; we've made a +<a href="ftp://ftp.cygnus.com/pub/egcs/infrastructure/dejagnu-971028.tar.gz"> +dejagnu snapshot available until a new version of dejagnu can be released. + + +How to build a cross compiler + Building cross compilers is a rather complex undertaking because they +usually need additional software (cross assembler, cross linker, target +libraries, target include files, etc). + + We recommend reading the <a href="ftp://ftp.cygnus.com/pub/embedded/crossgcc/FAQ-0.8.1"> +crossgcc FAQ for information about building cross compilers. + + If you have all the pieces available, then `make cross' should build a +cross compiler. `make LANGUAGES="c c++" install'will install the cross +compiler. + + Note that if you're trying to build a cross compiler in a tree which +includes binutils-2.8 in addition to egcs, then you're going to need to +make a couple minor tweaks so that the cross assembler, linker and +nm utilities will be found. + +binutils-2.8 builds those files as gas.new, ld.new and nm.new; egcs gcc +looks for them using gas-new, ld-new and nm-new, so you may have to arrange +for any symlinks which point to <file>.new to be changed to <file>-new. + + +Snapshots, how, when, why + We make snapshots of the egcs sources about once a week; there is no +predetermined schedule. These snapshots are intended to give everyone +access to work in progress. Any given snapshot may generate incorrect code +or even fail to build. + +If you plan on downloading and using snapshots, we highly recommend you +subscribe to the egcs mailing lists. See <a href="index.html#mailinglists"> +mailing lists on the main egcs page for instructions on how to subscribe. + +When using the diff files to update from older snapshots to newer snapshots, +make sure to use "-E" and "-p" arguments to patch so that empty files are +deleted and full pathnames are provided to patch. If your version of +patch does not support "-E", you'll need to get a newer version. Also note +that you may need autoconf, autoheader and various other programs if you use +diff files to update from one snapshot to the next. + + +How to install both egcs and gcc2 +It may be desirable to install both egcs and gcc2 on the same system. This +can be done by using different prefix paths at configure time and a few +symlinks. + +Basically, configure the two compilers with different --prefix options, +then build and install each compiler. Assume you want "gcc" to be the egcs +compiler and available in /usr/local/bin; also assume that you want "gcc2" +to be the gcc2 compiler and also available in /usr/local/bin. + +The easiest way to do this is to configure egcs with --prefix=/usr/local/egcs +and gcc2 with --prefix=/usr/local/gcc2. Build and install both compilers. +Then make a symlink from /usr/local/bin/gcc to /usr/local/egcs/bin/gcc and +from /usr/local/bin/gcc2 to /usr/local/gcc2/bin/gcc. Create similar links +for the "g++", "c++" and "g77" compiler drivers. + + +Problems building Linux kernels +If you installed a recent binutils/gas snapshot on your Linux system, +you may not be able to build the kernel because objdump does not understand +the "-k" switch. The solution for this problem is to remove /usr/bin/encaps. + +You may get an internal compiler error compiling process.c in newer +versions of the Linux kernel on x86 machines. This is a bug in an asm +statement in process.c, not a bug in egcs. XXX How to fix?!? + +You may get errors with the X driver of the form +_X11TransSocketUNIXConnect: Can't connect: errno = 111 + +It's a kernel bug. The function sys_iopl in arch/i386/kernel/process.c +does an illegal hack which used to work but is now broken since GCC optimizes +more aggressively . The newer 2.1.x kernels already have a fix which should +also work in 2.0.32. + + +Virtual memory exhausted error + This error means your system ran out of memory; this can happen for large +files, particularly when optimizing. If you're getting this error you should +consider trying to simplify your files or reducing the optimization level. + +Note that using -pedantic or -Wreturn-type can cause an explosion in the +amount of memory needed for template-heavy C++ code, such as code that uses +STL. Also note that -Wall includes -Wreturn-type, so if you use -Wall you +will need to specify -Wno-return-type to turn it off. + + +GCC can not find GAS +Some configurations like irix4, irix5, hpux* require the use of the GNU +assembler intead of the system assembler. To ensure that egcs finds the GNU +assembler, you should configure the GNU assembler with the same --prefix +option as you used for egcs. Then build & install the GNU assembler. + + +egcs does not work on Red Hat 5.0 + egcs does not currently work with Red Hat 5.0; we'll update this +entry with more information as it becomes available. + + +Last modified: December 2, 1997 |