
%         Registration           Kdump, A Kexec based kernel crash dumping    
%                                                mechanism                    
%                              Vivek Goyal (vgoyal@in.ibm.com)                

Kdump is a kexec-based kernel crash dumping      
mechanism, which is being perceived as a       
reliable crash dumping solution for Linux. In  
this paper we discuss what kexec is and what   
it can do in general case. Kexec has been      
modified to boot a new kernel even in a system 
crash event. This paper includes the details   
about the changes made in kexec to handle the  
panic situations. Given the fact that kexec    
enables booting into a new kernel while        
preserving the memory contents in a crash      
scenario, kdump uses this feature to capture   
the kernel crash dump. Physical memory layout  
and processor state are encoded in ELF Core    
format and these headers are stored in a       
reserved section of memory. Upon a crash, new  
kernel boots up from reserved memory and       
provides a platform to retrieve stored elf     
headers and capture the crash dump. We briefly 
discuss elf core header creation and dump      
capture mechanism and also detail how to       
configure and use kdump feature.               



