Hi Geert,
On 11/05/2013 03:15 PM, Geert Uytterhoeven wrote:
Hi,
I'm trying to play a bit with Linux on OpenRISC using a DE0-Nano board.
Basically I followed the instructions on http://kevinmehall.net/openrisc/guide/.
That works fine (most of the time).
Great to have you looking into this stuff! Some more experienced "Linux
eyes" on this code is very much welcome.
PC is 0x0028c174:
c028c11c <enable_mmu>:
c028c11c: b7 c0 00 11 l.mfspr r30,r0,0x11
c028c120: 1b 80 00 00 l.movhi r28,0x0
c028c124: ab 9c 00 60 l.ori r28,r28,0x60
c028c128: e3 de e0 04 l.or r30,r30,r28
c028c12c: c0 00 f0 11 l.mtspr r0,r30,0x11
c028c130: 15 00 00 00 l.nop 0x0
c028c134: 15 00 00 00 l.nop 0x0
c028c138: 15 00 00 00 l.nop 0x0
c028c13c: 15 00 00 00 l.nop 0x0
c028c140: 15 00 00 00 l.nop 0x0
c028c144: 15 00 00 00 l.nop 0x0
c028c148: 15 00 00 00 l.nop 0x0
c028c14c: 15 00 00 00 l.nop 0x0
c028c150: 15 00 00 00 l.nop 0x0
c028c154: 15 00 00 00 l.nop 0x0
c028c158: 15 00 00 00 l.nop 0x0
c028c15c: 15 00 00 00 l.nop 0x0
c028c160: 15 00 00 00 l.nop 0x0
c028c164: 15 00 00 00 l.nop 0x0
c028c168: 15 00 00 00 l.nop 0x0
c028c16c: 15 00 00 00 l.nop 0x0
c028c170: 15 00 00 05 l.nop 0x5
--> c028c174: 84 79 00 00 l.lwz r3,0x0(r25)
See commit dec830189e1e192a80f574243a2dc31bdc1c4fc5. r25 is supposed to
contain a pointer to the FDT at this point... since you're using a
built-in DTB this value will presumably be garbage and there's no sanity
checking on the value.
r3 (see patch) should really contain a "no FDT" value when the kernel is
launched but I don't see that that's being done.
Stefan... any thoughts on this? I take it you never use a built-in
kernel? What does u-boot do if there's no FDT to pass to the kernel?
/Jonas
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