(ok, it's my turn to ask dumb questions again.) following up on a previous post of mine, i'm still trying to clarify the issues related to building and running a new kernel, and header files. historically, of course, the kernsl source has always been dumped under /usr/src/linux-2.x.yy or something to that effect. and, from memory, it was always recommended to create the symlink /usr/src/linux to point at the source directory for the currently running kernel. why was this? IIRC, it's because other builds needed access to the kernel header files for the currently-running kernel so they could be created compatible, is that about right? and, from tradition, those builds would look for /usr/src/linux to get access to the header files. but there is now a glibc-kernheaders RPM for red hat, so is there any need for that symlink any more? i certainly don't bother creating it any more since i moved up to the 2.5 kernel, and i've never had any problems. but there's also the issue that, certainly, the header files included in glibc-kernheaders, being part of a fixed RPM, are not going to keep up with the possibly updated header files in the new kernel source tree. there's no reason to expect that a newer kernel source tree won't have, perhaps, updated header files. so it's reasonable to expect that there might be differences between the header files in the glibc-kernheaders RPM and those in the source tree for the current kernel. can anyone clarify that relationship? in addition, if there is no further need for the /usr/src/linux symlink, this suggests that there's no need for the kernel source tree to be under /usr/src (which was a silly place for it all the time, since it prevented /usr from being mounted read-only). as long as kernel and RPM builds took place under /usr/src, it kept /usr from really being available for RO mounting. is there anything to stop one from downloading and building a new kernel elsewhere? or perhaps making /usr/src a symlink to something outside /usr, so /usr can finally be mounted read-only unless you explicitly want to make some changes? in short, the questions: 1) what is the relationship between the header files in the glibc-kernheaders RPM and those in the (unrelated) kernel source tree? 2) is there any need for the historical /usr/src/linux symlink to the actual kernel source tree anymore? 3) if an application truly needs access to the header files for the current kernel, is it now official to get them via the symlink /lib/modules/2.5.xx/build? (which, of course, makes the /usr/src/linux symlink redundant.) 4) is it necessary to build new kernels under /usr/src, or can the kernel source and build be located anywhere at this point? 5) can one just use a symlink to move /usr/src out of /usr once and for all? 6) is there a doc or URL that covers all this? thanks. -- Robert P. J. Day Eno River Technologies Unix, Linux and Open Source training Waterloo, Ontario www.enoriver.com
