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Re: [XenPPC] [pushed] [ppc] FPSCR and XER are really 64 bit quantities


On Apr 25, 2006, at 4:08 PM, Hollis Blanchard wrote:

On Tue, 2006-04-25 at 14:14 -0400, Jimi Xenidis wrote:
changeset:   9950:249f22f51bb31148f896be0c7e85618b20f8c5fd
tag:         tip
user:        jimix@xxxxxxxxxxxxxxxxxxxxx
date:        Tue Apr 25 15:04:52 2006 -0400
files: xen/arch/ppc/float.S xen/arch/ppc/gdbstub.c xen/arch/ ppc/ppc64/exceptions.S xen/include/public/arch-ppc64.h
description:
[ppc] FPSCR and XER are really 64 bit quantities

Neither the PEM PDF (page 64) nor the Architecture Book I PDF (ver 2.02,
page 97) agree with you about FPSCR. Please explain?

look at the original:
http://lists.xensource.com/archives/html/xen-ppc-devel/2006-04/ msg00050.html

it is explained in the rest of the comment:
  - FPSCR should be save/restored with stfd/lfd since the 32 bit form
    can mangle the value.

The PEM PDF (again page 64) contradicts the Architecture Book I PDF
(page 42), which is unfortunate, but I'm ok with that change.

If you are questioning the XER here, you need to look at the 64bit PEM (pem_64bit_v3.0.2005jul15.pdf)
on page 50. Snippet below if you don't have it.

Attachment: pastedGraphic.pdf
Description: Adobe PDF document

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