Re: Re: [lkcd-devel] Re: Re: lcrash and debian

Jeff Haran wrote:

>
>Here at Brocade we have a cross version of crash that executes on linux x86 platforms (e.g. PCs) and which analyzes dumps obtained from PowerPC platforms (e.g our FibreChannel switches). The code came to us from MontaVista, who was then where we got our kernels from, but I had to make several fixes to it in order to get it to deal properly with loadable modules. This code deals with the big-endian/little-endian issue, PC's being little and PowerPCs being big.
>
>One of the other complexities is dealing with the varying ways that page tables are organized on different PowerPC processors. On some PowerPC variants, PTEs are 32 bits. On others, they are 64 bits due to the 64 bit physical addresses that those processors implement (my understanding is that the same issue exists among x86 variants, those with and without PAE). crash has to deal with these differences if it is to make sense of the page tables contained in the dump files. Changing the code to deal with these differences at run time was something that I couldn't figure out how to do (and I really didn't have the time to do), so I opted to create two versions, one for each PTE size.
>
>Having spent a non-trivial amount of time looking at this code, I think creating a cross version of crash that will properly analyze dumps from any other processor and any kernel configuration would be a very difficult problem. There are just too many variables to deal with at run-time.
>
>Jeff Haran
>Brocade Communications Systems
>
>  
>
Jeff,

I have recently spent quite a bit of time with this code, and I have 
most of the PowerPC variants working.  Of course, there are always going 
to be problems with variants of processors (ARM and PPC are notoriously 
bad).  But what I have works pretty well, and it's a ton better than not 
having anything.

-Corey


-------------------------------------------------------
This SF.net email is sponsored by: IT Product Guide on ITManagersJournal
Use IT products in your business? Tell us what you think of them. Give us
Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more
http://productguide.itmanagersjournal.com/guidepromo.tmpl