1 files changed, 125 insertions, 0 deletions

diff --git a/src/kernel/blk_drv/ramdisk.c b/src/kernel/blk_drv/ramdisk.c
new file mode 100644
index 0000000..dc99f7c
--- /dev/null
+++ b/src/kernel/blk_drv/ramdisk.c
@@ -0,0 +1,125 @@
+/*
+ *  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;
+}