Tom,
I am looking at your 2012 presentation.
It would be very helpful if you color-coded the different areas with an
indication of who can write to them.
For example, in an F8SA, code the fields that are set/used by the
program allocating the save-area red. Thus indicating that those bytes
can not be touched by the program that is later called.
Tony Thigpen
Tom Marchant wrote on 1/27/22 4:27 PM:
On Thu, 27 Jan 2022 20:39:26 +0000, Seymour J Metz <sme...@gmu.edu> wrote:
I don't understand "That is not what F8SA was designed for.";
the text you cited confirms that an F8SA is used by routines that
need to save ARs.
No, that isn't what it says. It says "F8SA area provides space into
which a program called by the creator of the save area can save
both ARs and 64-bit GPRs".
It is not for programs that need to save ARs, but for programs
that call other programs that need to save ARs. If you use F8SA
the way you are suggesting, you'd better not call another
program that will use F7SA format to save your registers.
The part of the manual describing F8SA is titled "If changing the
contents of bits 0-31 of the 64-bit GPRs but not changing ARs".
The only save area format that is documented for saving Access
Registers is the F7SA.
Tom Marchant
