Re: [RFC][BUG] tracer: Fails to work

[Steven Rostedt]

On Thu, 28 Jan 2016 16:29:57 +0100
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Thu, Jan 28, 2016 at 02:53:53PM +0000, Mathieu Desnoyers wrote:
> > On x86, many BIOS wipe the memory content even after a warm reset :(
> > The most reliable solution I found on x86 is to use kexec() to
> > boot into a new kernel, mount the DAX filesystem again and read the
> > buffers from there.  
> 
> kexec() is tricky when the kernel is still prefectly fine, I doubt it'll
> work when I've hosed it properly :/

I use it all the time when a kernel crashes. Well, kexec and kdump.
Which by the way, the crash utility has a way to read the ftrace ring
buffer from a kexec kdump core file.

-- Steve