cc/gcc/egcs kernel compilation options?

[Daniel Jacobowitz]

On Thu, Jul 01, 1999 at 10:49:57PM +0000, Barrie Spence wrote:
> 
> As a PPC newbie, why do we need/use "-msoft-float"? Is this 
> to handle some processor implementations that don't have 
> floating-point hardware? (and if so, does it have any overhead 
> on the 603/604/G3 Macs?). If it does have some cost, could it 
> not be enabled in the same way as on Intel?
> 
> Next question, is there any advantage to building a kernel
> with "-mcpu=604 -mtune=604"? (or whatever is most appropriate).

Floating point operations in the kernel are pretty rare, and thus do
not need to be optimized for speed; soft-float is thus acceptable.  The
advantage is that we don't need to save/restore the FPU registers and
state nearly as often.  And I do not know why x86 does not have this
issue.

Dan

/--------------------------------\  /--------------------------------\
|       Daniel Jacobowitz        |__|        SCS Class of 2002       |
|   Debian GNU/Linux Developer    __    Carnegie Mellon University   |
|         dan at debian.org         |  |       dmj+ at andrew.cmu.edu      |
\--------------------------------/  \--------------------------------/

[[ This message was sent via the linuxppc-dev mailing list.  Replies are ]]
[[ not  forced  back  to the list, so be sure to Cc linuxppc-dev if your ]]
[[ reply is of general interest. Please check http://lists.linuxppc.org/ ]]
[[ and http://www.linuxppc.org/ for useful information before posting.   ]]