I use crash 4.0-3.9 on a live 2.6.9-55 kernel on i386/i686 as root.<br><br>crash&gt; ls -l /dev/crash<br>crw-------&nbsp; 1 root root 10, 61 Mar&nbsp; 5 21:57 /dev/crash<br>crash&gt; ls -l /dev/mem<br>crw-r-----&nbsp; 1 root kmem 1, 1 Mar&nbsp; 5 16:49 /dev/mem<br>

crash&gt; q<br>[root@linux17081 ~]# ls -l /dev/crash /dev/mem<br>ls: /dev/crash: No such file or directory<br>crw-r-----&nbsp; 1 root kmem 1, 1 Mar&nbsp; 5 16:49 /dev/mem<br>[root@linux17081 ~]# id<br>uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel)<br>

<br>So, the /dev/crash file has write permission for me. The <br><br>I am attempting to change the content of some memory.<br><br>crash&gt; struct request_queue 0xf7b933f8<br>struct request_queue {<br>&nbsp; queue_head = {<br>

&lt;SNIP&gt;<br>...<br>}<br><br>crash&gt; struct -o request_queue | grep in_flight<br>&nbsp; [476] unsigned int in_flight;<br>crash&gt; eval 0xf7b933f8 + 476<br>hexadecimal: f7b935d4<br>&nbsp;&nbsp;&nbsp; decimal: 4156110292&nbsp; (-138857004)<br>

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; octal: 36756232724<br>&nbsp;&nbsp;&nbsp;&nbsp; binary: 11110111101110010011010111010100<br>crash&gt; rd f7b935d4<br>f7b935d4:&nbsp; fffffff1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ....<br>crash&gt; wr f7b935d4 0<br>wr: cannot write to /dev/crash!<br>

<br>I get the error above even if I change the ownership of /dev/kmem to root:root<br>crash&gt; ls -l /dev/mem<br>crw-r-----&nbsp; 1 root root 1, 1 Mar&nbsp; 5 16:49 /dev/mem<br><br>Am I doing something wrong? How do I change the content of memory on a live system using crash?<br>

<br>Dheeraj<br><br>