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47 lines
2.1 KiB
47 lines
2.1 KiB
20 years ago
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BTFIXUP
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-------
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To build new kernels you have to issue "make image". The ready kernel
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in ELF format is placed in arch/sparc/boot/image. Explanation is below.
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BTFIXUP is a unique feature of Linux/sparc among other architectures,
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developed by Jakub Jelinek (I think... Obviously David S. Miller took
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part, too). It allows to boot the same kernel at different
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sub-architectures, such as sun4c, sun4m, sun4d, where SunOS uses
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different kernels. This feature is convinient for people who you move
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disks between boxes and for distrution builders.
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To function, BTFIXUP must link the kernel "in the draft" first,
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analyze the result, write a special stub code based on that, and
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build the final kernel with the stub (btfix.o).
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Kai Germaschewski improved the build system of the kernel in the 2.5 series
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significantly. Unfortunately, the traditional way of running the draft
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linking from architecture specific Makefile before the actual linking
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by generic Makefile is nearly impossible to support properly in the
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new build system. Therefore, the way we integrate BTFIXUP with the
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build system was changed in 2.5.40. Now, generic Makefile performs
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the draft linking and stores the result in file vmlinux. Architecture
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specific post-processing invokes BTFIXUP machinery and final linking
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in the same way as other architectures do bootstraps.
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Implications of that change are as follows.
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1. Hackers must type "make image" now, instead of just "make", in the same
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way as s390 people do now. It is analogous to "make bzImage" on i386.
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This does NOT affect sparc64, you continue to use "make" to build sparc64
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kernels.
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2. vmlinux is not the final kernel, so RPM builders have to adjust
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their spec files (if they delivered vmlinux for debugging).
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System.map generated for vmlinux is still valid.
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3. Scripts that produce a.out images have to be changed. First, if they
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invoke make, they have to use "make image". Second, they have to pick up
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the new kernel in arch/sparc/boot/image instead of vmlinux.
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4. Since we are compliant with Kai's build system now, make -j is permitted.
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-- Pete Zaitcev
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zaitcev@yahoo.com
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