biosmem.c revision 53207 
1/*
2 * mjs copyright
3 *
4 * $FreeBSD: head/sys/boot/pc98/libpc98/biosmem.c 53207 1999-11-16 00:42:18Z nyan $
5 */
6
7/*
8 * Obtain memory configuration information from the BIOS
9 *
10 * Note that we don't try too hard here; knowing the size of
11 * base memory and extended memory out to 16 or 64M is enough for
12 * the requirements of the bootstrap.
13 *
14 * We also maintain a pointer to the top of physical memory
15 * once called to allow rangechecking of load/copy requests.
16 */
17#include <stand.h>
18#include "btxv86.h"
19
20vm_offset_t	memtop;
21
22/*
23 * Return base memory size in kB.
24 */
25int
26getbasemem(void)
27{
28#ifdef PC98
29    return ((*(u_char *)PTOV(0xA1501)&0x07)+1)*128;
30#else
31    v86.ctl = 0;
32    v86.addr = 0x12;		/* int 0x12 */
33    v86int();
34
35    return(v86.eax & 0xffff);
36#endif
37}
38
39/*
40 * Return extended memory size in kB
41 */
42int
43getextmem(void)
44{
45    int		extkb;
46
47#ifdef PC98
48    extkb = *(u_char *)PTOV(0xA1401)*128 + *(unsigned short *)PTOV(0xA1594)*1024;
49#else
50    v86.ctl = 0;
51    v86.addr = 0x15;		/* int 0x15 function 0x88*/
52    v86.eax = 0x8800;
53    v86int();
54    extkb = v86.eax & 0xffff;
55#endif
56
57    /* Set memtop to actual top or 16M, whicheve is less */
58    memtop = min((0x100000 + (extkb * 1024)), (16 * 1024 * 1024));
59
60    return(extkb);
61}
62
63