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Date: Wed, 30 Apr 2003 22:09:31 -0600
From: Grant Grundler <grundler@parisc-linux.org>
To: "Boehm, Hans" <hans_boehm@hp.com>
Cc: "'parisc-linux@lists.parisc-linux.org'" <parisc-linux@lists.parisc-linux.org>,
	'Carlos O'Donell' <carlos@baldric.uwo.ca>
Subject: Re: [parisc-linux] Program counter from sigcontext, constructurs and -fPIC
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On Tue, Apr 29, 2003 at 02:17:32PM -0700, Boehm, Hans wrote:
> 3) Adding 24 bytes to the struct sigcontext pointer (?) passed
>    as a third argument to the signal handler. (!)
...
> Is the third argument to a signal handler really not a pointer to sigcontext?

Yes - that seems to be the case.
Randolph found most of the answer in "Single Unix Specification"
(IEEE 1033.1-2001).  Third argument is "ucontext_t".

We counted 20 bytes (not 24) before the "struct sigcontext uc_mcontext;"
and thus still don't have a full explanation. Our best guess is some
misc padding is involved.

hth,
grant