Syslinux - Mar 2008 - Com32 api problem !

(sorry for my english if it is approximate !)

I want to access harddisk from com32 api with PXELINUX.
I try to use int 13h Extended Read Drive Parameters (48h), it doesn't works.
Here is my code, I have an error 1 in AH return code.
Int 13h Read Drive Parameters (08h) work well.

*******************************************************************************************
struct params {
  unsigned short size,info;
  unsigned long cylinders,heads,sectors;
  unsigned long long int total;
  unsigned short bytes;
} disk;

void ExtDiskInfo(int n)
{
  printf("ExtDiskInfo entry.\n");

  com32sys_t regs;
  memset(&regs,0,sizeof(regs));

  regs.eax.b[1] = 0x48;
  regs.edx.b[0] = 0x80 + n;
  regs.ds = SEG(__com32.cs_bounce);
  regs.esi.w[0]  = OFFS(__com32.cs_bounce);
  __intcall(0x13,&regs,&regs);

  if (regs.eax.b[1] == 0)
  {
    memcpy(&disk,__com32.cs_bounce,sizeof(struct params));
    size = disk.total * disk.bytes;
    printf("Total hard disk size : %lld Mb (%lld
sectors)\n",size>>20,disk.total);
  }
  else printf("Disk %d error : %d\n",n,regs.eax.b[1]);

  printf("ExtDiskInfo exit.\n");
}

*******************************************************************************************

Someone has a hint ?

Thanks.
PJL.

PERRIN Jean-Luc wrote:
> (sorry for my english if it is approximate !)
> 
> I want to access harddisk from com32 api with PXELINUX.
> I try to use int 13h Extended Read Drive Parameters (48h), it doesn't
works.
> Here is my code, I have an error 1 in AH return code.
> Int 13h Read Drive Parameters (08h) work well.
> 
You need to preinitialize the size field in the params structure before 
calling the interrupt.

     *(uint16_t *)__com32.cs_bounce = sizeof disk;

I suggest also zeroing out the input buffer:

     memset(__com32.cs_bounce, 0, sizeof disk);
     *(uint16_t *)__com32.cs_bounce = sizeof disk;

	-hpa

Great, it's work !

Thanks a lot.
PJL.

Hi

Could this code be modified to write to disk also (and if so, how)?
I need a simple com32 module which wipes the first 2048 bytes of the disk which
the system is using for localboot.

--Kjetil
> -----Original Message-----
> From: syslinux-bounces at zytor.com [mailto:syslinux-bounces at zytor.com]
On
> Behalf Of PERRIN Jean-Luc
> Sent: 25. mars 2008 18:49
> To: syslinux at zytor.com
> Subject: [syslinux] Com32 api problem !
>
> (sorry for my english if it is approximate !)
>
> I want to access harddisk from com32 api with PXELINUX.
> I try to use int 13h Extended Read Drive Parameters (48h), it doesn't
> works.
> Here is my code, I have an error 1 in AH return code.
> Int 13h Read Drive Parameters (08h) work well.
>
> ***********************************************************************
> ********************
> struct params {
>   unsigned short size,info;
>   unsigned long cylinders,heads,sectors;
>   unsigned long long int total;
>   unsigned short bytes;
> } disk;
>
> void ExtDiskInfo(int n)
> {
>   printf("ExtDiskInfo entry.\n");
>
>   com32sys_t regs;
>   memset(&regs,0,sizeof(regs));
>
>   regs.eax.b[1] = 0x48;
>   regs.edx.b[0] = 0x80 + n;
>   regs.ds = SEG(__com32.cs_bounce);
>   regs.esi.w[0]  = OFFS(__com32.cs_bounce);
>   __intcall(0x13,&regs,&regs);
>
>   if (regs.eax.b[1] == 0)
>   {
>     memcpy(&disk,__com32.cs_bounce,sizeof(struct params));
>     size = disk.total * disk.bytes;
>     printf("Total hard disk size : %lld Mb (%lld
> sectors)\n",size>>20,disk.total);
>   }
>   else printf("Disk %d error : %d\n",n,regs.eax.b[1]);
>
>   printf("ExtDiskInfo exit.\n");
> }
>
> ***********************************************************************
> ********************
>
> Someone has a hint ?
>
> Thanks.
> PJL.
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