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Code Issues Releases Activity

workaround painful vm86_datacall requirement that segment+offset

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must be withing the same PAGE frame
This commit is contained in:
Andrey A. Chernov 1998-09-29 04:09:39 +00:00
parent 1c4d62951a
commit bb2691312e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=39744
1 changed files with 14 additions and 5 deletions
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19
sys/i386/isa/vesa.c
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@ -23,7 +23,7 @@
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id: vesa.c,v 1.2 1998/09/23 09:59:00 yokota Exp $
* $Id: vesa.c,v 1.3 1998/09/25 11:55:46 yokota Exp $
*/
#include "sc.h"
@ -327,10 +327,13 @@ vesa_translate_flags(u_int16_t vflags)
static int
vesa_bios_init(void)
{
static u_char buf[512];
#define VESA_INFO_SIZE 512
static u_char buffer[VESA_INFO_SIZE * 2];
static u_char *buf = buffer;
struct vm86frame vmf;
struct vesa_mode vmode;
u_int32_t p;
u_short offset;
int modes;
int err;
int i;
@ -343,10 +346,16 @@ vesa_bios_init(void)
vesa_vmode[0].vi_mode = EOT;
bzero(&vmf, sizeof(vmf)); /* paranoia */
bzero(buf, sizeof(buf));
bcopy("VBE2", buf, 4); /* try for VBE2 data */
bzero(buffer, sizeof(buffer));
vmf.vmf_eax = 0x4f00;
err = vm86_datacall(0x10, &vmf, (char *)buf, sizeof(buf),
/* workaround - see vm86.c:vm86_datacall */
offset = (u_int)buf & PAGE_MASK;
if ((offset + VESA_INFO_SIZE) & PG_FRAME)
buf += PAGE_SIZE - offset;
bcopy("VBE2", buf, 4); /* try for VBE2 data */
err = vm86_datacall(0x10, &vmf, (char *)buf, VESA_INFO_SIZE,
&vmf.vmf_es, &vmf.vmf_di);
if ((err != 0) || (vmf.vmf_eax != 0x4f) || bcmp("VESA", buf, 4))
return 1;