PowerPC + SMP

Stuart Yoder stuart.yoder at conformative.com
Wed Apr 27 05:07:36 EST 2005

We've run into a few issues with U-boot, but they are not unsolveable--

-it doesn't provide an alternate execution path for the 2nd CPU when it
is started by the kernel
-U-boot needs to detect which CPU is executing
-U-boot on the 2nd CPU should not execute any platform/board specific
setup code-- this is stuff you only want to do once
-U-boot on the 2nd CPU cannot relocate itself to SDRAM because Linux is
already running there and assumes it owns all of memory
-it needs some way of getting to the Linux kernel entry point for
secondary CPUs
-it also appears that it should set up HID1 (other stuff??) for SMP


> -----Original Message-----
> From: Wolfgang Denk [mailto:wd at denx.de] 
> Sent: Tuesday, April 26, 2005 12:35 PM
> To: Stuart Yoder
> Cc: 'linuxppc-dev list'
> Subject: Re: PowerPC + SMP 
> In message <054301c54a6f$d1cf82b0$2f010a0a at foundation.com> you wrote:
> > 
> > I am using U-boot on my SMP system and U-boot is not SMP aware.  Do 
> > you
> Strictly speaking this statement is wrong.
> So far I am not aware of a port of U-Boot to a SMP system.  
> If  there was  such  a  port, and if it was properly done, 
> then U-Boot probably _were_ SMP aware.
> Best regards,
> Wolfgang Denk
> -- 
> Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
> Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: 
> wd at denx.de Every program has at least one bug and can be 
> shortened by  at  least one  instruction  --  from  which,  
> by induction, one can deduce that every program can be 
> reduced to one instruction which doesn't work.

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