Kernel memory usage optimisations?

["Marko Kenttälä" <marko.kenttala@teraflops.com>]

Hi,

I'm working on a project that uses Linux kernel version 2.4.16 on an 
embedded ARM device. Since we have limited memory (both RAM and Flash) I 
have tuned down some kernel internal defines to make it use less memory:

include/linux/major.h: MAX_CHRDEV 255->20, MAX_BLKDEV 255->10
include/linux/tty.h: MAX_NR_CONSOLES 63->3, MAX_NR_USER_CONSOLES 63->3
include/linux/kernel-stat.h: DK_MAX_MAJOR 16->4, DK_MAX_DISK 16->4
include/linux/sched.c: PIDHASH_SZ 1024->16
include/linux/tty.h: NR_PTYS 256->16, NR_LDISCS 16->4
kernel/printk.c: LOG_BUF_LEN 16384->2048

With these I have saved about 100 KB from bss. Do you see any dangerous 
side-effects in those modifications?

I understand that best area for saving memory usage is the C-library but 
are there any other kernel areas? I'm thinking of dropping swapfile support 
and maybe some other subsystems that are not needed in embedded device.

--
Marko Kenttälä, Software Engineer
TERAFLOPS Ltd., Member of Elektrobit Group
Mobile: +358 40 7501832, Fax: +358 3 2258484
http://www.teraflops.com, http://www.elektrobit.com