Re: Compat 32-bit syscall entry from 64-bit task!?

[H. Peter Anvin]

On 01/20/2012 02:40 PM, Roland McGrath wrote:
> If you change the size of a regset, then the new full size will be the size
> of the core file notes.  Existing userland tools will not be expecting
> this, they expect a known exact size.  If you need to add new stuff, it
> really is easier all around to add a new regset flavor.  When adding a new
> one, you can make it variable-sized from the start so as to be extensible
> in the future.  We did this for NT_X86_XSTATE, for example.
> 
> Thanks,
> Roland

Hi Roland,

What is needed to make a regset variable-sized?  Just declaring that it
may change in size in the future, or does one need a length field at the
top (I would personally have expected that both notes and ptrace would
have out-of-band methods for getting the size?)

	-hp-a

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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