hi,all:
i build an embedded linux on powerpc 405ep,i need execute floating point operation,and i enable "math emulate" option in kernel, i run a while(1)loop ,in the loop there was floating point expression ,after test ,i found the while (1) exit because of the floating point computation,that is the floating point can't execute on ppc stablely.Is there someone meets the same problems ,please give me some suggestion,thanks!!!
lily
hi,all:
i build an embedded linux on powerpc 405ep,i need execute floating
point operation,and i enable "math emulate" option in kernel, i run a
while(1)loop ,in the loop there was floating point expression ,after
test ,i found the while (1) exit because of the floating point
computation,that is the floating point can't execute on ppc
stablely.Is there someone meets the same problems ,please give me some
suggestion,thanks!!!
The 405ep has some errata on floating point use. I didn't work on the
processor so I don't know exactly what they are, but Timesys has a
toolchain just for the 405ep to work around the problem. The other
workaround we've used is much slower and it involved disabling the
hardware floating point unit in the head.s for the 405ep and turning on
the emulator. Just turning on the emulator is insufficient. The Timesys
toolchain isn't the only one out there specifically for the 405ep.
Greg Weeks
On Fri, Nov 11, 2005 at 07:51:31AM -0500, Greg Weeks wrote:
lily wrote:
quoted
hi,all:
i build an embedded linux on powerpc 405ep,i need execute floating
point operation,and i enable "math emulate" option in kernel, i run a
while(1)loop ,in the loop there was floating point expression ,after
test ,i found the while (1) exit because of the floating point
computation,that is the floating point can't execute on ppc
stablely.Is there someone meets the same problems ,please give me some
suggestion,thanks!!!
The 405ep has some errata on floating point use.
Are you sure it was 405ep? There is no floating point errata for this
chip due to the simple reason, it doesn't support floating point in
hardware at all.
You probably confusing it with 440ep.
I'm not aware of any 405ep specific toolchain. In fact, all what is
needed is simple 4xx specific toolchain with soft-float enabled by
default. This is how floating point is usually done for 4xx - just soft
emulation in user-space by the compiler without in-kernel emulation,
which is slow.
--
Eugene
On Fri, Nov 11, 2005 at 07:51:31AM -0500, Greg Weeks wrote:
quoted
lily wrote:
quoted
hi,all:
i build an embedded linux on powerpc 405ep,i need execute floating
point operation,and i enable "math emulate" option in kernel, i run a
while(1)loop ,in the loop there was floating point expression ,after
test ,i found the while (1) exit because of the floating point
computation,that is the floating point can't execute on ppc
stablely.Is there someone meets the same problems ,please give me some
suggestion,thanks!!!
The 405ep has some errata on floating point use.
Are you sure it was 405ep? There is no floating point errata for this chip due to the simple reason, it doesn't support floating point in hardware at all.
You probably confusing it with 440ep.
You're right. It was the 440ep. The 405ep BSP is using the 4xx toolchain. I don't think I've ever tried the math emulator on a 405.
Greg Weeks