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    SubjectRe: bug: kernel 3.0-rc3 not relocatable on i386?
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    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.

    Yes, I've got binutils-2.21 here. :/

    Petr


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