Xen devel - Aug 2004 - 2.4.26-xen0 unresolved symbol _mmx_memcpy in USB modules

Hi,

I''ve been playing with the 2.4.26 and 2.4.27 xen0 kernels, and at some
point I noticed that I was unable to load the USB modules anymore because
of an unresolved _mmx_memcpy symbol...A bit of fiddling with my settings showed
that when I build all my USB
modules in the kernel, the problem goes away, or alternately, if I switch
back from Athlon to Pentium II cpu (which was my original setting).
So for now I''m using the Pentium II as my CPU selection, but I was just
wondering if this is a known problem, or if I stumbled across something
new :-) ?
Warm regards,
Mark.





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> I''ve been playing with the 2.4.26 and 2.4.27 xen0 kernels, and at
some
> point I noticed that I was unable to load the USB modules anymore because
> of an unresolved _mmx_memcpy symbol...A bit of fiddling with my settings
showed that when I build all my USB
> modules in the kernel, the problem goes away, or alternately, if I switch
> back from Athlon to Pentium II cpu (which was my original setting).
> So for now I''m using the Pentium II as my CPU selection, but I was
just
> wondering if this is a known problem, or if I stumbled across something
> new :-) ?
I presume you''re doing a make clean and rebuilding everything
after changing the CPU type? 

I guess the only way we could be breaking this is if there was a
bug in our config script, but this part is copied from i386.

Ian


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In general, modules for different processors or subarchitectures are not 
cross compatible.  Modules compiled for Athlon will use MMX instructions 
to do fast memcopy, but a kernel compiled for Pentium II does not export 
the _mmx_memcpy symbol for modules to use - not because it''s not 
supported, but because it''s just not as fast on Pentium II.  You should
be able to use modules which are a strict ancestor of the current kernel 
architecture without problems - i.e. a 386 module in a Pentium II kernel 
should not cause grief.  YMMV.  I highly recommend using modules 
compiled for the same kernel configuration, however.

Cheers,
Zach

Mark Hurenkamp wrote:
>Hi,
>
>I''ve been playing with the 2.4.26 and 2.4.27 xen0 kernels, and at
some
>point I noticed that I was unable to load the USB modules anymore because
>of an unresolved _mmx_memcpy symbol...A bit of fiddling with my settings
showed that when I build all my USB
>modules in the kernel, the problem goes away, or alternately, if I switch
>back from Athlon to Pentium II cpu (which was my original setting).
>So for now I''m using the Pentium II as my CPU selection, but I was
just
>wondering if this is a known problem, or if I stumbled across something
>new :-) ?
>Warm regards,
>Mark.
>
>
>
>
>
>-------------------------------------------------------
>SF.Net email is sponsored by Shop4tech.com-Lowest price on Blank Media
>100pk Sonic DVD-R 4x for only $29 -100pk Sonic DVD+R for only $33
>Save 50% off Retail on Ink & Toner - Free Shipping and Free Gift.
>http://www.shop4tech.com/z/Inkjet_Cartridges/9_108_r285
>_______________________________________________
>Xen-devel mailing list
>Xen-devel@lists.sourceforge.net
>https://lists.sourceforge.net/lists/listinfo/xen-devel
>  
>


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My suspicion is that you have inconsistent build configurations for
your base kernel and USB modules. The latter is being built with
CONFIG_X86_USE_3DNOW, and therefore expects _mmx_memcpy. The base
kernel must be being built without CONFIG_X86_USE_3DNOW, as otherwise
that function is correctly EXPORT_SYMBOL()''ed by
arch/xen/kernel/i386-ksyms.c. 

 -- Keir
> Hi,
> 
> I''ve been playing with the 2.4.26 and 2.4.27 xen0 kernels, and at
some
> point I noticed that I was unable to load the USB modules anymore because
> of an unresolved _mmx_memcpy symbol...A bit of fiddling with my settings
showed that when I build all my USB
> modules in the kernel, the problem goes away, or alternately, if I switch
> back from Athlon to Pentium II cpu (which was my original setting).
> So for now I''m using the Pentium II as my CPU selection, but I was
just
> wondering if this is a known problem, or if I stumbled across something
> new :-) ?
> Warm regards,
> Mark.
> 
> 
> 
> 
> 
> -------------------------------------------------------
> SF.Net email is sponsored by Shop4tech.com-Lowest price on Blank Media
> 100pk Sonic DVD-R 4x for only $29 -100pk Sonic DVD+R for only $33
> Save 50% off Retail on Ink & Toner - Free Shipping and Free Gift.
> http://www.shop4tech.com/z/Inkjet_Cartridges/9_108_r285
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel


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