reboot

[Jason Chen]

hi,all,
Unlike normally,I built a MPC8248 system whose u-boot set flash locating from 0xfe000000 to 0xfe7fffff (8M),and burned the u-boot on 0xfe700000.
The HRCW was set to CIP = 0 which means that exceptions are vectored to the physical address 0xFFFn_nnnn.
The u-boot and kernel run successfully,but failed while execute the command reboot.I found kernel run m8260_gorom  below at the end of reboot be called.In these codes, MSR_ equal MSR_ME|MSR_RI originally,after be set to MSR_ME|MSR_RI|MSR_IP,the reboot can run successfully.
I wanna ask,in this case, is there a reset action? if there is, what cause it? if there is'nt, the cpu run to flash(0xfe700100) directly,then why MSR[ip] has to be set to 1? because in my system, exceptions address 0xfffn_nnnn did not exist at all.
And more,why my u-boot could run successfully while MSR[ip] = 1 but real exception vectors locate at 0xfe00_0n00?

    .globl  m8260_gorom /* r4 = addr in the rom,i set it to 0xfe700100 */
m8260_gorom:
	mfmsr	r0
	rlwinm	r0,r0,0,17,15	/* clear MSR_EE in r0 */
	sync
	mtmsr	r0
	sync
	mfspr	r11, HID0
	lis	r10, 0
	ori	r10,r10,HID0_ICE|HID0_DCE
	andc	r11, r11, r10
	mtspr	HID0, r11
	isync
	li	r5, MSR_
	lis	r6,2f at h
	addis	r6,r6,-KERNELBASE at h
	ori	r6,r6,2f at l
	mtspr	SRR0,r6
	mtspr	SRR1,r5
	isync
	sync
	rfi
2:
	mtlr	r4
	blr
                                  
Thanks very much!
Jason