From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 7 Aug 2002 11:23:02 -0500 From: Peter Bergner To: Paul Mackerras Cc: linuxPPC Dev , Mike Corrigan Subject: FP save/restore code in ppc32/ppc64 kernels Message-ID: <20020807162302.GA39680@congo.borg.umn.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: Paul, Can you describe (if you know/remember since a lot of this code has Cort's name on it) how the FP save/restore code is supposed to work? I'm wondering why we're clearing the MSR_FE{0,1} bits along with the MSR_FP bit. Is there a reason why they must be cleared when we clear the MSR_FP bit? The reason I ask is that someone was running some userland app that explicitly set the fpscr (using asm) and he got an FP exception even though gdb showed his MSR_FE{0,1} bits to be zero. This got me looking at the code which seems to be inherited old ppc32 code. I noticed that you've updated the ppc32, so before I update our ppc64 code, I'd like to understand more about how this is all supposed to work. Peter ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/