On Thu, Apr 27, 2023 at 07:54:56PM +0000, Seymour J Metz wrote:
> R1 is the table address; only 256 bytees need to be addressable. R2
> is the string address, and you need write access to everything up until
> the delimiter ('00'x in this case.)No! You need write access for at least 4K from the start of the string even if that's past the x'00'. >From z/Architecture Priciples of Operation for the TRE instruction: Access exceptions for the portion of the first operand to the right of the last byte processed may or may not be recognized. For an operand longer than 4K bytes, access exceptions are not recognized for locations more than 4K bytes beyond the last byte processed. His operand is 7fffffff long so it's longer than 4K so the at a minimum he needs write access to the 4K where the string starts and the next 4K too since the string doesn't start on a 4K boundary. That's probably why his 0C4 only happens sometimes -- it depends on the status/protect key of the next 4K block. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
