My question again isn’t this typical when writting SRB code You just have to remember instead of L RX,=A to do LA RX
> On Aug 23, 2021, at 12:10 PM, Charles Mills <[email protected]> wrote: > > Yes, it is trivial to write a program that relocates itself and is not > reliant on loader relocation of address constants. > > That was not my point. My point was that generally speaking programs are not > written that way, so moving "some" program with MVCL is not likely to result > in a usable image. > > Can be written that way does not equal guaranteed to be written that way. > > Charles > > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of Paul Gilmartin > Sent: Monday, August 23, 2021 2:30 AM > To: [email protected] > Subject: Re: Load Library Module Length and Load Macro Module Length > different Values > >> On Sun, 22 Aug 2021 17:04:20 -0700, Charles Mills wrote: >> >> Not what you asked, but can one MVCL a load module from one address to >> another and rely on its executing correctly? What about relocatable address >> constants? (Less necessary today than once upon a time due to LARL, but >> still lots of them around.) Of course in some case one might know that the >> load module in question was a table e.g. that had no RLDs. >> > https://en.wikipedia.org/wiki/Position-independent_code > > I was once modifying a Pascal compiler to generate code to run embedded, > on bare metal on 370-like processor. I added the capability to generate > position-independent_code (PIC). I generated all pointers self-relative, > used by the sequence: > USING *,R15 > ... > LA Rx,POINTER > AL Rx,POINTER > > Pascal has the limitation, useful in this case, of having no syntax to > statically initialize pointers in data areas. > > The MVCL test worked. > > For other reasons the product never made GA. > > I believed the 360 base-displacement hardware design facilitated PIC, > making RLDs unnecessary; OS designers ignored the capability. > > -- gil > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
