Re: [M68K/ColdFire patch 4/n] Remove kernel headers

[Maxim Kuvyrkov <maxim at codesourcery dot com>]

Andreas Schwab wrote:
> Maxim Kuvyrkov <maxim@codesourcery.com> writes:
>
> > This patch removes 2 kernel headers -- sigcontext.h and ucontext.h -- 
> > from GLIBC's m68k port. These headers are installed by the kernel,
> > that has a better idea of how it lays out the signal context.
> >
> > This elegant patch is a result of about a day of debugging unwinding
> > of the signal frames.
> >
> > Any comments?
>
> You are breaking the ABI.

Why?

For m68k the change is close to no-op, both kernel and GLIBC headers 
define the structures to be the same.

For ColdFire, there are two changes to GLIBC headers:

1. GLIBC headers set the size of the storage for FP registers to 8 
bytes.  While ColdFire FP register are 64-bit, the kernel does not 
distinguish between ColdFire and m68k in this case (and why should it?) 
and stores the FP registers to the 12-byte entries as on m68k.

2. GLIBC headers expect sigcontext structure to hold all 16 
general-purpose registers.  What is the foundation for this change from 
how m68k defines this structure?  The ColdFire kernel patches available 
at bitshrine.org do not change sigcontext.

Regards,

--
Maxim K.