Re: mmap local APIC address

[Vaibhav Jain <vjoss197@xxxxxxxxx>]

On Fri, Oct 14, 2011 at 9:10 PM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote:

hi...

On Sat, Oct 15, 2011 at 07:22, Vaibhav Jain <vjoss197@xxxxxxxxx> wrote:
> Hi,
>
> I am trying to map local APIC on an intel system (physical address
> 0xfee00000) in a user level program using mmap
> but my mmap is failing saying "Bad file descriptor". I am not sure if this
> problem is related to apic or
> mmap. I am running the program as root.  Please help me figure this out.

could you post the code?

anyway, check "man mmap" in "errors" section....the hint could be
found there.....

--
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

Hi,

Here's the code 



typedef unsigned int u32;

#define MAP_LEN                 0x1000  //4 KB page
#define BUFLEN 100
#define APIC_BASE               0xfee00000
#define APIC_ICR_low            0xfee00300
#define APIC_ICR_high           0xfee00310
#define APIC_ICR_init           0x00000500
#define APIC_ICR_start          0x00000600
#define APIC_ICR_ASSERT_LVL_TRG 0x0000c000
#define BOUNCE_CODE        0x2000

int apic_reset_cpu(cpu); 
int cpu = 2;

int main(){
if ((apic_reset_cpu(cpu)) != 0)
    printf("INIT & Startup failed!\n");
}


int apic_reset_cpu(int cpu)
{
  unsigned long tmpaddress, apic_icr, *apic_phy_addr;
  int fd, sleep_now=0;


  printf("Assuming APIC physical base: %lx \n", APIC_BASE);
  tmpaddress = (unsigned long) mmap(NULL, MAP_LEN, PROT_READ|PROT_WRITE, MAP_SHARED, fd, (off_t)APIC_BASE);
  
  if(tmpaddress == (unsigned long)MAP_FAILED) //check if it worked
  {
    perror("Mapping memory for absolute memory access failed.\n");
    return -3;
  }
  
  //prep ICR high
  apic_icr = tmpaddress;
  apic_icr |= APIC_ICR_high;
  apic_phy_addr = (unsigned long *) apic_icr;
  *apic_phy_addr = cpu << 24;
  
  //prep ICR low Send INIT and wait
  apic_icr = tmpaddress;
  apic_icr |= APIC_ICR_low;
  apic_phy_addr = (unsigned long *) apic_icr;
  *apic_phy_addr = APIC_ICR_init | APIC_ICR_ASSERT_LVL_TRG;
  sleep_now = usleep( 10000 ); //sleep 10 ms

  //prep for SIPI
  apic_icr = tmpaddress;
  apic_icr |= APIC_ICR_low;
  apic_phy_addr = (unsigned long *) apic_icr;
  *apic_phy_addr = APIC_ICR_start | (BOUNCE_CODE >> 12);
  sleep_now = usleep( 500 ); //sleep 500 usec 

  printf("Unmapping APIC Base page\n");
  tmpaddress &= 0xfffff000;
  munmap(tmpaddress, MAP_LEN);  
  
  return 0;
}

Thanks
Vaibhav Jain
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