Re: unresoved symbol _gp_disp
On Thu, Oct 04, 2007 at 08:29:59PM +0200, Andi Kleen wrote: > From: Andi Kleen <[EMAIL PROTECTED]> > Date: 04 Oct 2007 20:29:59 +0200 > To: "Steven J. Hill" <[EMAIL PROTECTED]> > Cc: veerasena reddy <[EMAIL PROTECTED]>, > linux-mips <[EMAIL PROTECTED]>, > "linux-kernel.org" > Subject: Re: unresoved symbol _gp_disp > Content-Type: text/plain; charset=us-ascii > > "Steven J. Hill" <[EMAIL PROTECTED]> writes: > > > > I have written a loadble module ( which gets complied > > > along with kernel) which does some floating point > > > operation. > > > > > NO FLOATING POINT in the kernel PERIOD. Either use integer > > operations, or redo your software architecture and do the > > floating point in userspace. > > You can use floating point; you just have to make sure to > save the FP context explicitely and disable preemption. Details > on how to do this vary by architecture. > > The problem is that FP code typically takes often a lot of CPU time > and it is quite antisocial to disable preemption for a long time > because that impacts real time latency for everybody. > > Besides many uses can be relatively easily rewritten to fixed > point. He said he was using software floating point which from a kernel perspective really just is integer stuff anyway. Hardware floating point in a MIPS kernel would be require solving a few interesting problems; the kernel floating point assist software is only designed to support userspace. Or alternativle well written FP code that avoids all the corner cases which would normally be handled by the kernel fp software. The biggest argument against floating point use in the kernel is that most of the time it's an indicator for poor division of work between kernel and userspace. Ralf - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: unresoved symbol _gp_disp
"Steven J. Hill" <[EMAIL PROTECTED]> writes: > > I have written a loadble module ( which gets complied > > along with kernel) which does some floating point > > operation. > > > NO FLOATING POINT in the kernel PERIOD. Either use integer > operations, or redo your software architecture and do the > floating point in userspace. You can use floating point; you just have to make sure to save the FP context explicitely and disable preemption. Details on how to do this vary by architecture. The problem is that FP code typically takes often a lot of CPU time and it is quite antisocial to disable preemption for a long time because that impacts real time latency for everybody. Besides many uses can be relatively easily rewritten to fixed point. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: unresoved symbol _gp_disp
> I have written a loadble module ( which gets complied > along with kernel) which does some floating point > operation. > NO FLOATING POINT in the kernel PERIOD. Either use integer operations, or redo your software architecture and do the floating point in userspace. -Steve - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: unresoved symbol _gp_disp
Steven J. Hill wrote: I have written a loadble module ( which gets complied along with kernel) which does some floating point operation. NO FLOATING POINT in the kernel PERIOD. Unless you compile your code with -msoft-float *and* also have a version of libgcc compiled with -mlong-calls -mno-abicalls -G0. If you do it that way, floating point works fine in the kernel (as long as you don't try to call sprintf with floating point parameters). Either use integer operations, or redo your software architecture and do the floating point in userspace. -Steve - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
