From owner-freebsd-hackers  Thu Feb 11 11:10:40 1999
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Date: Thu, 11 Feb 1999 14:07:56 -0500
To: freebsd-hackers@FreeBSD.ORG
From: "Md. Ahsan Habib" <mhabib@vt.edu>
Subject: /dev/kmem
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Hi
I am facing some problems to use /dev/kmem. I tried a lot, post it to the
news groups but couldn't come up to a solution. In one of my experiments I
need to write in /dev/kmem. I can't use normal file because it will consume
more time which will affect my experiments.

This is a sample code I tried to execute:

#include <fcntl.h>
#include <stdio.h>
#include <errno.h>

extern int errno;

int main()
{
        int fp,w,c;
        long l;
        char * Buff = "1234";

        fp = open("/dev/kmem", O_RDWR);
        if (fp == -1) {
                printf("open returned error\n");
                perror("open");
        }
        l = lseek(fp, 0x000a000,0);
        w = write(fp,Buff,4);
        c = close(fp);
        return 0;
}

It can open the file, change the  file pointer, close the file but can't
write anything in the file. The value of w is always -1. I tried with
several locations instead of the beginning one 0x000a000.

I set all necessary mod and ownership.

I will be happy if anyone can help me. It's really important to me.

Sincerely,

--Ahsan Habib
Department of Computer Science
Virginia Tech.



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