Pete, You should NOT use control registers for the following reasons: 1) They are slow to load and store (especially under VM) 2) If you do get it to work you cannot use the function for which the control register was designed 3) If you use unassigned bits future architectural changes will cause unpredictable results in your case 4) Future arch changes might change the registers contents without you knowing it. The overhead of loading/storing in the psa is very low, I think it actually faster then loading/storing access registers.
Jan Jaeger >From: Pete Zaitcev <[EMAIL PROTECTED]> >Reply-To: Linux on 390 Port <[EMAIL PROTECTED]> >To: [EMAIL PROTECTED] >Subject: Putting current in register >Date: Fri, 21 Jun 2002 00:23:19 -0400 > >Since interrupt stacks were split, current sits in the prefix page. >Did anyone think about returning it into a register? I am not >sufficiently familiar with the architecture to figure it out. >Candidates include control 10 (PER start), control 15 (Linkage), >and GPR 12. Possibly I missed something. > >I was thinking about abusing X15, but it seems that applications >may do some mischief trying "extract saved registers" instructions. >PER appears to be used, I am not sure if that's actually the case. >So, I am zooming on R12. Anyone wants to comment? > >-- Pete _________________________________________________________________ MSN Foto's is de makkelijkste manier om je foto's te delen met anderen en af te drukken: http://photos.msn.nl/Support/WorldWide.aspx
