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start [2017-01-21 22:30] joshtriplett Fix typo. |
start [2020-07-06 21:24] joshtriplett Drop instructions for kernels older than 3.17-rc1, |
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| ====== Building a tiny kernel ====== | ====== Building a tiny kernel ====== | ||
| - | With Linux 3.17-rc1 and newer, ''make tinyconfig'' will produce a minimal kernel. You can then turn on the minimal set of options you need. | + | With current Linux (since 3.17-rc1 and newer, ''make tinyconfig'' will produce a minimal kernel. You can then turn on the minimal set of options you need. |
| - | + | ||
| - | On previous kernels, you'll need to take a few additional steps to make the kernel as small as possible: | + | |
| - | + | ||
| - | * Prior to 3.15-rc1, ''make allnoconfig'' did not turn off options behind CONFIG_EXPERT or CONFIG_EMBEDDED, so you'll have to do so manually. | + | |
| - | * Change the allocator from SLUB to SLOB | + | |
| - | * Change the kernel compression method from GZIP to XZ | + | |
| - | * Disable HIGHMEM4G, using NOHIGHMEM instead | + | |
| - | * Set ''CONFIG_OPTIMIZE_INLINING=y'' | + | |
| - | * Set ''CONFIG_CC_OPTIMIZE_FOR_SIZE=y'' | + | |
| You'll want to target the most code-size-efficient architecture supported by your target machine; for instance, on x86 systems, build a 32-bit kernel rather than a 64-bit kernel. On current kernels, ''make allnoconfig'' should do this automatically. | You'll want to target the most code-size-efficient architecture supported by your target machine; for instance, on x86 systems, build a 32-bit kernel rather than a 64-bit kernel. On current kernels, ''make allnoconfig'' should do this automatically. | ||
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| You can find the latest tinification changes in Josh Triplett's tree at https://git.kernel.org/cgit/linux/kernel/git/josh/linux.git/ , in the tiny/* branches. Note that tiny/next gets reset for each new merge window, and other tiny/* branches may be recreated or rebased. | You can find the latest tinification changes in Josh Triplett's tree at https://git.kernel.org/cgit/linux/kernel/git/josh/linux.git/ , in the tiny/* branches. Note that tiny/next gets reset for each new merge window, and other tiny/* branches may be recreated or rebased. | ||
| + | |||
| + | ====== Searching for tinification opportunities ====== | ||
| + | On a built kernel, try running ''nm --size-sort vmlinux''. This will show all the symbols in vmlinux, sorted by size. | ||
| ====== Use Cases ====== | ====== Use Cases ====== | ||
| See the [[Use Cases]] page. | See the [[Use Cases]] page. | ||
start.txt · Last modified: 2020-07-06 21:27 by joshtriplett
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