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Old 04-30-2009, 10:08 AM   #1
payu21
LQ Newbie
 
Registered: Apr 2009
Location: australia
Posts: 12

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Do i need integer to hex conversion, if yes how???


hie all,

-------------------------------------------------
void Clear_ControlPort_bit(int a)

{
int t;
printf("a=%i\n",a);

if(a<8)

{

if(a==0||a==1||a==3)
{
printf("reading controlport\n");
printf("identifier = %d \n",_BV(a));
printf("p = %d \n",p);
a = p|_BV(a);

/* not going to read loop but taking p value*/
printf("a=%i\n",a);

Write_ControlPort(a);


}
//else

//Write_ControlPort(t&~_BV(a));

}
return;

-----------------------------------------------------------------*/

void Write_ControlPort(int a)

{
printf("writing to port\n");
outb(a,ControlPort);
return;

}
------------------------
Do i need to convert the value of a to hex before writing to control port??? Because its showing a segmentation fault at "outb"

please help me
 
Old 04-30-2009, 10:30 AM   #2
johnsfine
LQ Guru
 
Registered: Dec 2007
Distribution: Centos
Posts: 5,286

Rep: Reputation: 1181Reputation: 1181Reputation: 1181Reputation: 1181Reputation: 1181Reputation: 1181Reputation: 1181Reputation: 1181Reputation: 1181
How about a little context of what you are trying to do?

I don't know what weird device you might be trying to control, so I'm a tiny bit short of 100% certain no form of conversion to hex is required before writing to its port. (That answers your explicit question).

Linux is a protected OS, so ordinary code can't ordinarily write to ports. So that is probably the source of the fault.

If you have done something to make writing to that port valid, that should have been part of the context you should have provided for your question.

If you haven't done anything to make writing to that port valid, here is the first link I found just now googling the topic:
http://www.faqs.org/docs/Linux-mini/...ing.html#ss2.1
It seems to be a good explanation of the basics.

Last edited by johnsfine; 04-30-2009 at 10:35 AM.
 
  


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