approx 2k reduction in kernel code size -- 300 bytes in data (patch)

approx 2k reduction in kernel code size -- 300 bytes in data (patch)

[Manuel Novoa III]

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Hello all,

Sunday afternoon I felt like taking I break so I started looking at the
elks kernel.  After doing lots of repetitive bcc-specific optimizations,
as well as reworking a few things (arch/i86/lib/memmove.c and kernel/sys.c
in particular -- I'd appreciate a second pair of eyes on those), this is
what I have for the config file below.

   cvs source (with fs/minix/bitmap.c fix):
	Root device is (0, 0)
	Boot sector 512 bytes.
	Setup is 1772 bytes.
	System is 120672 B (61456 B code, 7940 B data and 51276d B bss)
	System is 69428

   cvs source with attached patch:
	Root device is (0, 0)
	Boot sector 512 bytes.
	Setup is 1772 bytes.
	System is 118380 B (59472 B code, 7640 B data and 51268d B bss)
	System is 67144

So, a savings of just under 2k in code and 300 bytes in data.

bcc optimizations used mainly fell under the following categories:

1) Reworked codeflow for better bcc code generation.
2) Use of "register char *"s as counters, as bcc can't seem to place
   ints in registers.  (yes, this is ugly, but it is effective)
3) Allocation of different register variables in different blocks in
   on subroutine, as bcc seems to limit you to two register variables
   active at a time (di/si).
4) Collection of common work.

Hopefully in a couple of weeks I'll have some time to look at the
driver files as well.

Enjoy.

Manuel




Modified files:

	arch/i86/lib/
		bitops.c	memmove.c

	arch/i86/mm/
		init.c		malloc.c

	fs/
		block_dev.c	devices.c	exec.c		fcntl.c
		file_table.c	inode.c		ioctl.c		namei.c
		open.c		pipe.c		read_write.c	readdir.c
		select.c	stat.c		super.c

	fs/minix/
		bitmap.c	file.c		inode.c		namei.c
		symlink.c

	kernel/
		exit.c		fork.c		printk.c	sched.c
		signal.c	sleepwake.c	sys.c		time.c

	lib/
		chqueue.c	string.c



Config file - activated options:

CONFIG_ARCH_AUTO=y
CONFIG_PC_AUTO=y
CONFIG_CONSOLE_DIRECT=y
CONFIG_DCON_VT52=y
CONFIG_DCON_ANSI=y
CONFIG_KEYMAP_US=y
CONFIG_CHAR_DEV_RS=y
CONFIG_CHAR_DEV_LP=y
CONFIG_CHAR_DEV_MEM=y
CONFIG_PSEUDO_TTY=y
CONFIG_BLK_DEV_BIOS=y
CONFIG_BLK_DEV_BFD=y
CONFIG_BLK_DEV_BHD=y
CONFIG_GENDISK=y
CONFIG_BLK_DEV_CHAR=y
CONFIG_MINIX_FS=y
CONFIG_FS_EXTERNAL_BUFFER=y
CONFIG_PIPE=y
CONFIG_EXEC_MINIX=y
CONFIG_SOCKET=y
CONFIG_INET=y
CONFIG_INET_STATUS=y
CONFIG_SYS_VERSION=y
CONFIG_ROOTDEV_FD0=y







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