Messages in this thread | | | Subject | Re: bug: kernel 3.0-rc3 not relocatable on i386? | From | Petr Tesarik <> | Date | Wed, 15 Jun 2011 14:26:23 +0200 |
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Petr Tesarik píše v St 15. 06. 2011 v 12:07 +0200: > Petr Tesarik píše v St 15. 06. 2011 v 12:01 +0200: > > Maarten Lankhorst píše v St 15. 06. 2011 v 11:21 +0200: > > > Hi Petr, > > > > > > 2011/6/15 Petr Tesarik <ptesarik@suse.cz>: > > > > Hi all, > > > > > > > > it seems that the 3.0-rc3 kernel is not relocatable on i386. I get > > > > warnings about jiffies being an absolute symbol, and indeed, when GRUB > > > > loads the kernel at a non-default address, jiffies is not relocated. > > > > > > > > In my example the kernel is configured with > > > > CONFIG_PHYSICAL_START=0x1000000 > > > > CONFIG_PHYSICAL_ALIGN=0x200000 > > > > CONFIG_RELOCATABLE=y > > > > and loaded at 0x200000 by GRUB. > > > > > > > > Booting fails when checking whether the timer works, because do_timer() > > > > increments jiffies_64, but timer_irq_works() checks jiffies. The code > > > > looks like this: > > > > > > > > c13daab7: 8b 3d 40 7a 39 c1 mov 0xc1397a40,%edi > > > > > > > > but arch/x86/boot/compressed/vmlinux.relocs does not contain c13daaba. > > > > Consequently, timer_irq_works() reads the wrong memory location and > > > > fails, causing a panic: > > > > > > > > kernel panic: IO-APIC + timer doesn't work! Boot with apic=debug and > > > > send a report. Then try booting with the 'noapic' option. > > > > > > > > Needless to say, the kernel freezes a few initcalls later when booted > > > > with noapic, because IO-APIC worked fine, in fact. I verified that by > > > > inserting a debugging printk() in do_timer(), and I also verified with > > > > that printk() that the address of jiffies_64 and the address of jiffies > > > > differ at run time. > > > > > > > > Any idea how to fix this? > > > Does reverting this commit fix it? > > > > Isn't this related to VDSO? I've got no troubles with the VDSO. It's > > just that the kernel assumes a fixed location of jiffies (in the kernel > > direct mapping), so it cannot be relocated. > > > > OTOH this must have worked the other day, so searching for the commit > > that broke it is a good hint. I'll try it here, too. > > Ah, it turns out this is in fact reported here: > > http://sourceware.org/bugzilla/show_bug.cgi?id=12327 > > But the patch was reverted by commit > 6b35eb9ddcddde7b510726de03fae071178f1ec4, so these binutils have been > broken again since January.
I tried to understand what was wrong with the approach taken by Shaohua and what caused a problem for Markus Trippelsdorf, but it seems the revert didn't help in any way: I don't get build failures. I get a non-booting kernel, and the traces didn't give me any clue what was wrong.
Anyway, what's wrong with the generic approach suggested by hpa?
http://linux.derkeiler.com/Mailing-Lists/Kernel/2011-01/msg06976.html
Petr
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