2.11BSD#431 - /usr/src/sys/pdp/ram.c

   1: /*
   2:  * ISR 'ramdisk' driver.
   3:  * This driver implements a 'ram disk' in main memory.
   4:  *
   5:  * For the block device, the driver works by remapping buffer header
   6:  * addresses and simply returning.  This way the buffer copy is done only
   7:  * once.  It is faster than any mass storage device in access time and
   8:  * transfer time (both are immediate) and consumes less cpu time in the
   9:  * driver than most.
  10:  *
  11:  * Gregory Travis, Institute for Social Research, September 1984
  12:  * Mucked about, KB, March 1987.
  13:  * Remucked and stomped, Casey Leedom, August 1987.
  14:  */
  15: 
  16: #include "ram.h"
  17: #if NRAM > 0
  18: #include "param.h"
  19: #include "../machine/seg.h"
  20: 
  21: #include "buf.h"
  22: #include "user.h"
  23: #include "conf.h"
  24: #include "map.h"
  25: #include "systm.h"
  26: #include "dk.h"
  27: 
  28: #ifdef UCB_METER
  29: static  int ram_dkn = -1;       /* number for iostat */
  30: #endif
  31: 
  32: u_int       ram_size = NRAM;    /* (patchable) ram disk size */
  33: memaddr     ram_base;       /* base of ram disk area */
  34: 
  35: /*
  36:  * Allocate core for ramdisk(s)
  37:  */
  38: size_t
  39: raminit()
  40: {
  41:     if (ram_size) {
  42:         if (ram_base = malloc(coremap, ram_size*btoc(NBPG))) {
  43: #ifdef UCB_METER
  44:             dk_alloc(&ram_dkn, 1, "ram", 0L);
  45: #endif
  46:             return(ram_size*btoc(NBPG));
  47:         }
  48:         printf("ram: nospace\n");
  49:     }
  50:     return(0);
  51: }
  52: 
  53: ramopen(dev)
  54:     dev_t dev;
  55: {
  56:     if (minor(dev) || !ram_base)
  57:         return (ENXIO);
  58:     return (0);
  59: }
  60: 
  61: ramstrategy(bp)
  62:     register struct buf *bp;
  63: {
  64:     register memaddr ramaddr;
  65: 
  66:     if (!ram_base) {
  67:         printf("ram: not allocated\n");
  68:         bp->b_error = ENXIO;
  69:         bp->b_flags |= B_ERROR;
  70:         goto done;
  71:     }
  72:     if(bp->b_blkno < 0 ||
  73:         ((bp->b_blkno + ((bp->b_bcount+(NBPG-1)) >> PGSHIFT)) > ram_size)) {
  74:         bp->b_error = EINVAL;
  75:         bp->b_flags |= B_ERROR;
  76:         goto done;
  77:     }
  78: #ifdef UCB_METER
  79:     if (ram_dkn >= 0) {
  80:         dk_xfer[ram_dkn]++;
  81:         dk_wds[ram_dkn] += bp->b_bcount>>6;
  82:     }
  83: #endif
  84:     ramaddr = ram_base + bp->b_blkno * btoc(NBPG);
  85:     if (bp->b_flags & B_PHYS)
  86:         ramstart(ramaddr, bp);
  87:     else if (bp->b_flags & B_READ) {
  88: #ifdef DIAGNOSTIC
  89:         if(bp->b_flags & B_RAMREMAP)
  90:             panic("ram: remap!");
  91: #endif
  92:         bp->b_flags |= B_RAMREMAP;  /* block read (sic) */
  93:         bp->b_un.b_addr = (caddr_t)(ramaddr << 6);
  94:         bp->b_xmem = (ramaddr >> 10) & 077;
  95:     } else
  96:         if ((bp->b_flags & B_RAMREMAP) == 0)
  97:             ramstart(ramaddr, bp);  /* virgin write */
  98: done:
  99:     iodone(bp);
 100: }
 101: 
 102: /*
 103:  * Start transfer between ram disk (ramaddr) and buffer.  Actually completes
 104:  * synchronously of course, but what the heck.
 105:  */
 106: ramstart(ramaddr, bp)
 107:     memaddr ramaddr;
 108:     register struct buf *bp;
 109: {
 110:     register u_int n, c;
 111:     memaddr bufaddr;
 112:     caddr_t seg6addr;
 113:     int error;
 114: 
 115:     if (!(n = bp->b_bcount))
 116:         return;
 117: #ifdef UCB_METER
 118:     if (ram_dkn >= 0)
 119:         dk_busy |= 1 << ram_dkn;
 120: #endif
 121:     bufaddr = bftopaddr(bp);        /* click address of buffer */
 122:     seg6addr = SEG6 + ((u_int)bp->b_un.b_addr & 077);
 123:     c = MIN(n, (SEG6+8192)-seg6addr);
 124:     for (;;) {
 125:         if (bp->b_flags & B_READ) {
 126:             mapseg5(ramaddr, ((btoc(8192)-1)<<8)|RO);
 127:             if (error = fmove(bufaddr, ((btoc(8192)-1)<<8)|RW,
 128:                 SEG5, seg6addr, c))
 129:                 break;
 130:         } else {
 131:             mapseg5(ramaddr, ((btoc(8192)-1)<<8)|RW);
 132:             if (error = fmove(bufaddr, ((btoc(8192)-1)<<8)|RO,
 133:                 seg6addr, SEG5, c))
 134:                 break;
 135:         }
 136:         if (!(n -= c))
 137:             break;
 138:         ramaddr += btoc(8192);
 139:         bufaddr += btoc(8192);
 140:         seg6addr = SEG6;
 141:         c = MIN(n, 8192);
 142:     }
 143:     normalseg5();
 144: #ifdef UCB_METER
 145:     if (ram_dkn >= 0)
 146:         dk_busy &= ~(1 << ram_dkn);
 147: #endif
 148:     if (error) {
 149:         bp->b_error = error;
 150:         bp->b_flags |= B_ERROR;
 151:     }
 152: }
 153: #endif NRAM

Defined functions

Defined variables