Hi, On Mon, Jan 14, 2008 at 01:41:20PM -0500, Steven Rostedt wrote: > We are pleased to announce the 2.6.24-rc7-rt2 tree, which can be > downloaded from the location: > > http://rt.et.redhat.com/download/ > .......... > Changes since 2.6.24-rc7-rt1 > .......... > - PPC compile fix (reported by: Robert Schwebel) > Compiling with tracing function turned seemed still to be broken to me: kernel/built-in.o: In function `early_printk_name': latency_trace.c:(.text+0x3cd18): undefined reference to `early_printk' latency_trace.c:(.text+0x3cd40): undefined reference to `early_printk' kernel/built-in.o: In function `early_print_entry': latency_trace.c:(.text+0x3cd80): undefined reference to `early_printk' latency_trace.c:(.text+0x3cdd8): undefined reference to `early_printk' latency_trace.c:(.text+0x3cdfc): undefined reference to `early_printk' We made a early_printk patch based on the 8250_early for powerpc 32bit here. (still absolutely untested and incomplete, we will post it asap). I added early_printk() and exported _mcount() and could compile succesfully. However the kernel will not boot. I attached a bdi to it and found out that it stucks at _mcount in arch/powerpc/kernel/entry_32.S at about line 1080, where the variable mcount_enabled is loaded and checked. Obviously the variable is still not valid at the time of check. To check this I took out the lines like above --- arch/powerpc/kernel/entry_32.S.orig 2008-01-15 17:01:25.000000000 +0100 +++ arch/powerpc/kernel/entry_32.S 2008-01-15 17:17:18.000000000 +0100 @@ -1075,9 +1075,6 @@ stw r6, 24(r1) mflr r3 /* will use as first arg to __trace() */ mfcr r4 - lis r5,mcount_enabled@ha - lwz r5,mcount_enabled@l(r5) - cmpwi r5,0 stw r3, 44(r1) /* lr */ stw r4, 8(r1) /* cr */ stw r7, 28(r1) After recompiling the kernel started normally and it seems to work. I was even able to make a trace with cyclictest. However there were several crashes (which might be caused by other problems). I still have to take a closer look. I am just wondering why the check for mcount_enabled is there at all and I think that there due to be some better fixes than just throw it out ;-). On the other side, I just can't find in which way mcount_enabled is used in the tracer at all. Could you give me some hints on this one? cheers Luotao Fu -- Dipl.-Ing. Luotao Fu | Phone: +49-5121-206917-3 Pengutronix - Linux Solutions for Science and Industry Entwicklungszentrum Nord http://www.pengutronix.de
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