On 2 June 2011 19:56, Paul Gilmartin <[email protected]> wrote: > On Thu, 2 Jun 2011 16:29:44 -0700, Edward Jaffe wrote: >> >>Not pre-zeroed per se, but the pages are in first-reference state. >> > Is this a hardware feature? (I haven't a PoOp (PrOp) handy.) > > If not, I could envision doing it in software: point the page > table entry at a physical page containing zeroes; widely shared, > and entirely write-protected. Then a protection exception > could be handled as if it were a page fault. > > Is it worth the cost of implementation, whether done in hardware > or in software? It's merely coddling programmers who perform > a fetch long before they store to the same location.
It's not *wrong* or even misleading or obscure, as long as you know that the storage contains zeroes. If you obtained the storage using a form of STORAGE OBTAIN or GETMAIN that guarantees to give you zeroed storage, then where's the problem? > They deserve to be treated according to the second definition of "coddle" > rather than the first. It's not merely a matter of coddling programmers (even ovoid ones); the system cannot hand out storage that contains someone else's data, even if you didn't ask for it to contain zeroes. Tony H. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
