path: root/Documentation/sparc/README-2.5
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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/sparc/README-2.5
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+To build new kernels you have to issue "make image". The ready kernel
+in ELF format is placed in arch/sparc/boot/image. Explanation is below.
+BTFIXUP is a unique feature of Linux/sparc among other architectures,
+developed by Jakub Jelinek (I think... Obviously David S. Miller took
+part, too). It allows to boot the same kernel at different
+sub-architectures, such as sun4c, sun4m, sun4d, where SunOS uses
+different kernels. This feature is convinient for people who you move
+disks between boxes and for distrution builders.
+To function, BTFIXUP must link the kernel "in the draft" first,
+analyze the result, write a special stub code based on that, and
+build the final kernel with the stub (btfix.o).
+Kai Germaschewski improved the build system of the kernel in the 2.5 series
+significantly. Unfortunately, the traditional way of running the draft
+linking from architecture specific Makefile before the actual linking
+by generic Makefile is nearly impossible to support properly in the
+new build system. Therefore, the way we integrate BTFIXUP with the
+build system was changed in 2.5.40. Now, generic Makefile performs
+the draft linking and stores the result in file vmlinux. Architecture
+specific post-processing invokes BTFIXUP machinery and final linking
+in the same way as other architectures do bootstraps.
+Implications of that change are as follows.
+1. Hackers must type "make image" now, instead of just "make", in the same
+ way as s390 people do now. It is analogous to "make bzImage" on i386.
+ This does NOT affect sparc64, you continue to use "make" to build sparc64
+ kernels.
+2. vmlinux is not the final kernel, so RPM builders have to adjust
+ their spec files (if they delivered vmlinux for debugging).
+ System.map generated for vmlinux is still valid.
+3. Scripts that produce a.out images have to be changed. First, if they
+ invoke make, they have to use "make image". Second, they have to pick up
+ the new kernel in arch/sparc/boot/image instead of vmlinux.
+4. Since we are compliant with Kai's build system now, make -j is permitted.
+-- Pete Zaitcev