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diff --git a/README.txt b/README.txt new file mode 100644 index 000000000..482f8ea5b --- /dev/null +++ b/README.txt @@ -0,0 +1,67 @@ + + Kernel package tips & tricks. + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The kernel is one of the more complicated packages in the distro, and +for the newcomer, some of the voodoo in the spec file can be somewhat scary. +This file attempts to document some of the magic. + + +Speeding up make prep +--------------------- +The kernel is nearly 500MB of source code, and as such, 'make prep' +takes a while. The spec file employs some trickery so that repeated +invocations of make prep don't take as long. Ordinarily the %prep +phase of a package will delete the tree it is about to untar/patch. +The kernel %prep keeps around an unpatched version of the tree, +and makes a symlink tree clone of that clean tree and than applies +the patches listed in the spec to the symlink tree. +This makes a huge difference if you're doing multiple make preps a day. +As an added bonus, doing a diff between the clean tree and the symlink +tree is slightly faster than it would be doing two proper copies of the tree. + + +build logs. +----------- +There's a convenience helper script in scripts/grab-logs.sh +that will grab the build logs from koji for the kernel version reported +by make verrel + + +config heirarchy. +----------------- +Instead of having to maintain a config file for every arch variant we build on, +the kernel spec uses a nested system of configs. At the top level, is +config-generic. Add options here that should be present in every possible +config on all architectures. +Beneath this are per-arch overrides. For example config-x86-generic add +additional x86 specific options, and also _override_ any options that were +set in config-generic. +There exist two additional overrides, config-debug, and config-nodebug, +which override -generic, and the per-arch overrides. It is documented +further below. + +debug options. +-------------- +This is a little complicated, as the purpose & meaning of this changes +depending on where we are in the release cycle. +If we are building for a current stable release, 'make release' has +typically been run already, which sets up the following.. +- Two builds occur, a 'kernel' and a 'kernel-debug' flavor. +- kernel-debug will get various heavyweight debugging options like + lockdep etc turned on. + +If we are building for rawhide, 'make debug' has been run, which changes +the status quo to: +- We only build one kernel 'kernel' +- The debug options from 'config-debug' are always turned on. +This is done to increase coverage testing, as not many people actually +run kernel-debug. + +To add new debug options, add an option to _both_ config-debug and config-nodebug, +and also new stanzas to the Makefile 'debug' and 'release' targets. + +Sometimes debug options get added to config-generic, or per-arch overrides +instead of config-[no]debug. In this instance, the options should have no +discernable performance impact, otherwise they belong in the debug files. + |