From mboxrd@z Thu Jan 1 00:00:00 1970 Cc: Seong-kyu Ko , linuxppc-embedded@lists.linuxppc.org Message-ID: <39AABEC8.4DDE4CA0@lucent.com> Date: Mon, 28 Aug 2000 14:34:32 -0500 From: Tom Roberts MIME-Version: 1.0 To: cal_erickson@mvista.com Subject: Re: Problems of the corss-compiler. References: <39AAA991.32FDF058@mvista.com> Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Cal Erickson wrote: > In the MSR of the PPC processor there is a bit > that indicates whether there is hardware > floating point unit available. Beware -- Linux uses the bit to optimize FP-register usage in the kernel. Basically it starts each process with the bit off, but turns it on for a process which takes the "FP not avail" trap. The optimization occurs in context switches where the FP registers are not saved or restored for processes with this bit off. This is, of course, for CPUs which have FP units.... IIRC the CPUs without FP units have the bit hardwired to 0. Tom Roberts tjroberts@lucent.com ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/