/* *  linux/kernel/blk_drv/ramdisk.c * *  Written by Theodore Ts'o, 12/2/91 */#include <string.h>#include <linux/config.h>#include <linux/sched.h>#include <linux/fs.h>#include <linux/kernel.h>#include <asm/system.h>#include <asm/segment.h>#include <asm/memory.h>#define MAJOR_NR 1#include "blk.h"char	*rd_start;int	rd_length = 0;void do_rd_request(void){	int	len;	char	*addr;	INIT_REQUEST;	addr = rd_start + (CURRENT->sector << 9);	len = CURRENT->nr_sectors << 9;	if ((MINOR(CURRENT->dev) != 1) || (addr+len > rd_start+rd_length)) {		end_request(0);		goto repeat;	}	if (CURRENT-> cmd == WRITE) {		(void ) memcpy(addr,			      CURRENT->buffer,			      len);	} else if (CURRENT->cmd == READ) {		(void) memcpy(CURRENT->buffer, 			      addr,			      len);	} else		panic("unknown ramdisk-command");	end_request(1);	goto repeat;}/* * Returns amount of memory which needs to be reserved. */long rd_init(long mem_start, int length){	int	i;	char	*cp;	blk_dev[MAJOR_NR].request_fn = DEVICE_REQUEST;	rd_start = (char *) mem_start;	rd_length = length;	cp = rd_start;	for (i=0; i < length; i++)		*cp++ = '\0';	return(length);}/* * If the root device is the ram disk, try to load it. * In order to do this, the root device is originally set to the * floppy, and we later change it to be ram disk. */void rd_load(void){	struct buffer_head *bh;	struct super_block	s;	int		block = 256;	/* Start at block 256 */	int		i = 1;	int		nblocks;	char		*cp;		/* Move pointer */		if (!rd_length)		return;	printk("Ram disk: %d bytes, starting at 0x%x\n", rd_length,		(int) rd_start);	if (MAJOR(ROOT_DEV) != 2)		return;	bh = breada(ROOT_DEV,block+1,block,block+2,-1);	if (!bh) {		printk("Disk error while looking for ramdisk!\n");		return;	}	*((struct d_super_block *) &s) = *((struct d_super_block *) bh->b_data);	brelse(bh);	if (s.s_magic != SUPER_MAGIC)		/* No ram disk image present, assume normal floppy boot */		return;	nblocks = s.s_nzones << s.s_log_zone_size;	if (nblocks > (rd_length >> BLOCK_SIZE_BITS)) {		printk("Ram disk image too big!  (%d blocks, %d avail)\n", 			nblocks, rd_length >> BLOCK_SIZE_BITS);		return;	}	printk("Loading %d bytes into ram disk... 0000k", 		nblocks << BLOCK_SIZE_BITS);	cp = rd_start;	while (nblocks) {		if (nblocks > 2) 			bh = breada(ROOT_DEV, block, block+1, block+2, -1);		else			bh = bread(ROOT_DEV, block);		if (!bh) {			printk("I/O error on block %d, aborting load\n", 				block);			return;		}		(void) memcpy(cp, bh->b_data, BLOCK_SIZE);		brelse(bh);		printk("\010\010\010\010\010%4dk",i);		cp += BLOCK_SIZE;		block++;		nblocks--;		i++;	}	printk("\010\010\010\010\010done \n");	ROOT_DEV=0x0101;}