I believe the question should be sent to u-boot@lists.denx.de, not linuxppc-dev list.
What is the TLB settings for NAND FCM buffer? Pay attention to set the TLB as cache inhibited and guarded attribute.
If not set the guarded bit, it is possible to cause the speculate load from FCM buffer below the cmplwi and blt inst.
IIRC, the FCM buffer only has the 4KB. So if it has one speculated Load above the 4KB, it will run into problem.
The 0x700 is not alignment exception, it is program exception.
If you can dump the exception error information from console to us, maybe we can give better help.
Thanks, Dave
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From: linuxppc-dev-bounces+daveliu=freescale.com@lists.ozlabs.org [mailto:linuxppc-dev-bounces+daveliu=freescale.com@lists.ozlabs.org] On Behalf Of Fahd Abidi Sent: Friday, June 19, 2009 4:34 AM To: linuxppc-dev@ozlabs.org Subject: Problem with memcpy on ppc8536 Hello, I am trying to debug a crash during memcpy while copying data from the FCM buffer of an mpc8536 to the ddr ram. I debugged memcpy enough through my BDI3000 to see that the entire contents of the fcm buffer I want moved are actually moved off to memory location I specify. The crash comes after it memcpy finishes copying and performs the instruction "2: cmplwi 0,r5,4": memcpy: rlwinm. r7,r5,32-3,3,31 /* r0 = r5 >> 3 */ addi r6,r3,-4 addi r4,r4,-4 beq 2f /* if less than 8 bytes to do */ andi. r0,r6,3 /* get dest word aligned */ mtctr r7 bne 5f 1: lwz r7,4(r4) lwzu r8,8(r4) stw r7,4(r6) stwu r8,8(r6) bdnz 1b andi. r5,r5,7 2: cmplwi 0,r5,4 contents of r5 are 0x0 showing that the entire 0x1000 size transfer I specified correctly finished. At this point I can check the memory contents through my BDI and verify all the data is in the ddr as I expect. Now the strange thing happens, if I execute the "cmplwi 0,r5,4" the program takes an exception and eventually gets struck at exception vector 0x700 which I saw from start.S is an "Alignment" exception. I am not sure what this exception means, can someone help me understand what is happening? Does this exception somehow mean that memcpy did not move all the data? Does memcpy expect contents of r5 to be 4 and not 0 when it hits the cmplwi instruction?
Fahd Abidi Product Manager - Technical Tools and Development Ultimate Solutions, Inc. ================================================================ Your Single Source for Professional Development Tools and Embedded Solutions Ph: 978-455-3383 x255 Fx: 978-926-3091 Email: fabidi@ultsol.com Visit: http://www.ultsol.com http://www.ultsol.com/