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Date: Fri, 23 Jan 2015 12:37:06 -0600 From: Tom Zanussi <tom.zanussi@...ux.intel.com> To: josh@...htriplett.org Cc: linux-kernel@...r.kernel.org, Tom Zanussi <tom.zanussi@...ux.intel.com> Subject: [PATCH 00/10] tinification: Make memory-access char devices optional This patchset adds a top-level config option, CONFIG_DEVMEM_BASE, and a series of dependent options below it which allow various devices such as /dev/mem, /dev/null, /dev/zero, /dev/random, etc. to be disabled. This allows embedded systems systems that don't need any or all of those devices to save the kernel memory associated with those devices. It also adds a related option to disable the getrandom(2) syscall, CONFIG_GETRANDOM_SYSCALL, which allows code shared between it and /dev/*random to be compiled out as well. Disabling of CONFIG_DEVMEM_BASE and its dependent options is only available if CONFIG_EMBEDDED is enabled; normal systems will still have everything enabled as usual. bloat-o-meter shows a total 6k savings for a tinyconfig kernel with all options disabled, and about 10k savings for the same thing but using defconfig. bloat-o-meter (based on tinyconfig): add/remove: 0/55 grow/shrink: 1/3 up/down: 332/-6563 (-6231) function old new delta extract_entropy 114 446 +332 __print_once 13 12 -1 write_null 3 - -3 read_null 3 - -3 mix_pool_bytes 17 14 -3 aio_read_null 3 - -3 pipe_to_null 4 - -4 mem_class 4 - -4 write_full 6 - -6 devkmsg_release 15 - -15 random_fasync 16 - -16 mmap_zero 16 - -16 aio_write_null 18 - -18 open_port 19 - -19 random_read 20 - -20 splice_write_null 24 - -24 null_lseek 25 - -25 mmap_mem_ops 32 - -32 mem_devnode 35 - -35 mmap_kmem 37 - -37 random_write 42 - -42 xfer_secondary_pool 60 - -60 write_pool 82 - -82 random_poll 83 - -83 read_iter_zero 95 - -95 urandom_read 96 - -96 memory_open 96 - -96 devkmsg_poll 97 - -97 read_port 98 - -98 mmap_mem 103 - -103 devkmsg_open 112 - -112 write_port 116 - -116 zero_fops 120 - -120 urandom_fops 120 - -120 random_fops 120 - -120 port_fops 120 - -120 null_fops 120 - -120 memory_fops 120 - -120 mem_fops 120 - -120 kmsg_fops 120 - -120 kmem_fops 120 - -120 full_fops 120 - -120 memory_lseek 122 - -122 devkmsg_llseek 144 - -144 chr_dev_init 162 3 -159 read_mem 162 - -162 extract_buf 164 - -164 _random_read.part 173 - -173 account 181 - -181 write_mem 184 - -184 devlist 192 - -192 extract_entropy_user 197 - -197 devkmsg_write 209 - -209 sys_getrandom 211 - -211 zero_bdi 244 - -244 read_kmem 290 - -290 random_ioctl 319 - -319 write_kmem 349 - -349 devkmsg_read 699 - -699 The following changes since commit 5eb11d6b3f55eb4d28c51ea7f641c0e5e255a70f: Merge tag 'sound-3.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound (2015-01-21 20:37:25 +1200) are available in the git repository at: git://git.yoctoproject.org/linux-yocto-contrib.git tzanussi/devmem-tinification-v1 http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-contrib/log/?h=tzanussi/devmem-tinification-v1 Tom Zanussi (10): drivers/char: Support compiling out memory-access char devices drivers/char: Support compiling out /dev/mem drivers/char: Support compiling out /dev/port drivers/char: Support compiling out /dev/null drivers/char: Support compiling out /dev/zero drivers/char: Support compiling out /dev/full drivers/char: Support compiling out /dev/random drivers/char: Support compiling out /dev/urandom drivers/char: Support compiling out /dev/kmsg drivers/char: Support compiling out the getrandom(2) syscall arch/x86/Kconfig.debug | 1 + drivers/char/Kconfig | 109 ++++++++++++++++++++++++++++++++++++++++++++++++- drivers/char/mem.c | 83 +++++++++++++++++++++++++++---------- drivers/char/random.c | 24 ++++++++--- kernel/printk/printk.c | 2 + kernel/sys_ni.c | 1 + 6 files changed, 192 insertions(+), 28 deletions(-) -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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