Re: [PATCH] MIPS/Linux: Signal frame support for DSP registers

["Maciej W. Rozycki" <macro at codesourcery dot com>]

On Mon, 21 May 2012, Eli Zaretskii wrote:

> >  Eli, can you tell me if the NEWS entry is OK with you?
> 
> Yes, thanks.

 Great!  I'll push the change then.

> > Please note that I deliberately say "Linux" rather than "GNU/Linux"
> > here as all the DSP support relies on a kernel feature; it does not
> > rely on any C library or other userland feature whatsoever.
> 
> Hmm... since you mention that, I looked into configure.tgt and saw
> that we are inconsistent here: some targets are described as running
> "GNU/Linux", others just "Linux".  Personally, I think "GNU/Linux" is
> the more correct in this case (you refer to a target system), but it's
> not my call.

 After some thinking I've concluded it's an interesting question actually.  
Some target properties are libc-specific, for example the system library 
is free to map any magic numbers used for kernel syscalls however it likes 
(things like fcntl flags or whatever) and the library calls may not 
identity map to syscalls, so these will be libc- rather than 
kernel-specific.

 Here I don't think the system library can do anything, the signal frame 
and the associated bits are arranged by the kernel directly and the layout 
of struct ucontext_t is cast in stone.  One can stuff a hypothetical BSD C 
library on top of the Linux kernel and our MIPS DSP support will work with 
that unchanged.

 A less hypothetical case is an embedded app running on Linux without libc 
and I believe such stuff actually exists (and GDB can debug it provided 
that they have a remote stub of some sort available).

 Thanks for your notes.

  Maciej