On Mon, 11 Mar 2019 18:38:49 -0700 Joel Fernandes <joelaf@xxxxxxxxxx> wrote: > On Mon, Mar 11, 2019 at 6:28 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > > > On Mon, 11 Mar 2019 20:39:12 -0400 > > Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote: > > > > > I think even though the kernel-headers can't have information about all data > > > structures, they do already contain a lot of data structure definitions we > > > need already. And anything needed can/should arguably be moved to include/ if > > > they are really needed for kernel extension by something "external" to the > > > kernel such as kernel modules or eBPF, right? > > > > That's not my worry. I would like to be able to easily walk data > > structures from within the kernel, without having to do a lot of work > > in userspace to get that information. The kprobe_events could then be > > passed type casts or such to access data fields of arguments to > > functions and such. > > Ok. > > > > In any case, such a solution such as what Steve suggested, still cannot do > > > what we can with headers - such as build kernel modules on the fly using the > > > C-compiler without any auto-generation of C code from any debug artifiacts. > > > Think systemtap working with the module-backend without any need for > > > linux-headers package on the file system. So such a solution would still be a > > > bit orthogonal in scope to what this proposed solution can solve IMO. > > > > > > > With the information I would like to have, it would be trivial to read > > the data to create the header files needed for modules. > > But there are macros and other #define things too. We lose all of them > and can't recreate them from just DWARF (AFAIK). Including > include/generated/autoconf.h which #defines the CONFIG options. For > that we either need headers, or full kernel's sources with build > artifacts. What kind of macros would you concern? > I do see a use case for the debug info you are talking about as you > mentioned for the kprobe_events argument list types, and I already > thought about it. But it does not seem to work for all the use cases I > am referring to here. But the eBPF is based on kprobe-events. What kind of usage would you expected? (with macros??) Thank you, -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
