Re: Compile pvops kernel xen/stable-2.6.32.x error

[Jeremy Fitzhardinge <jeremy@goop.org>]

 On 10/27/2010 09:55 AM, Teck Choon Giam wrote:
> Hi,
>
> I pulled from git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git
> and do the following:
>
> git checkout -b xen/stable-2.6.32.x --track origin/xen/stable-2.6.32.x
> git pull
>
> git log showing the latest commit as below:
>
> commit d0054d672ff0ebf6116cee27bae3fc2591c726af
> Author: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> Date:   Mon Oct 25 16:53:46 2010 -0700
>
>     x86/pvclock: zero last_value on resume
>
>     If the guest domain has been suspend/resumed or migrated, then the
>     system clock backing the pvclock clocksource may revert to a smaller
>     value (ie, can be non-monotonic across the migration/save-restore).
>     Make sure we zero last_value in that case so that the domain
>     continues to see clock updates.
>
>     Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
>     (cherry picked from commit 29acbb4e1d93e719250648db1ce8c7a24144fd86)
>
>
> I am using gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-48) in CentOS5.
>
> Anyone encountered the below warnings & errors?
>
> -----SNAP-----
> arch/x86/kernel/smpboot.c:99: warning: function declaration isn’t a prototype
> arch/x86/kernel/smpboot.c:104: warning: function declaration isn’t a prototype
> -----SNAP-----
> arch/x86/xen/enlighten.c: In function ‘xen_init_cpuid_mask’:
> arch/x86/xen/enlighten.c:242: warning: unused variable ‘dx’
> arch/x86/xen/enlighten.c:242: warning: unused variable ‘cx’
> arch/x86/xen/enlighten.c:242: warning: unused variable ‘bx’
> arch/x86/xen/enlighten.c:242: warning: unused variable ‘ax’
>   CC      arch/x86/xen/setup.o - due to target missing
>   CC      arch/x86/xen/multicalls.o - due to target missing
>   CC      arch/x86/xen/mmu.o - due to target missing
> arch/x86/xen/mmu.c:163: error: __pcpu_scope_xen_cr3 causes a section
> type conflict
> arch/x86/xen/mmu.c:164: error: __pcpu_scope_xen_current_cr3 causes a
> section type conflict
> arch/x86/xen/mmu.c:163: error: __pcpu_unique_xen_cr3 causes a section
> type conflict
> arch/x86/xen/mmu.c:164: error: __pcpu_unique_xen_current_cr3 causes a
> section type conflict
> make[2]: *** [arch/x86/xen/mmu.o] Error 1
> make[1]: *** [arch/x86/xen] Error 2
> make: *** [arch/x86] Error 2

Ah, how unpleasant.  Unfortunately the problem isn't really with the
lines its pointing out, but with something earlier in the source (or
headers) which is also per-cpu, and gcc has decided there's a section
conflict between the two.  Could you do "make arch/x86/mmu.i" and send
me the result?

Thanks,
    J

> -----SNAP-----
>
> The errors in arch/x86/xen/mmu.c line 163 and 164 are:
>
> /*
>  * Note about cr3 (pagetable base) values:
>  *
>  * xen_cr3 contains the current logical cr3 value; it contains the
>  * last set cr3.  This may not be the current effective cr3, because
>  * its update may be being lazily deferred.  However, a vcpu looking
>  * at its own cr3 can use this value knowing that it everything will
>  * be self-consistent.
>  *
>  * xen_current_cr3 contains the actual vcpu cr3; it is set once the
>  * hypercall to set the vcpu cr3 is complete (so it may be a little
>  * out of date, but it will never be set early).  If one vcpu is
>  * looking at another vcpu's cr3 value, it should use this variable.
>  */
> DEFINE_PER_CPU(unsigned long, xen_cr3);  /* cr3 stored as physaddr */
> DEFINE_PER_CPU(unsigned long, xen_current_cr3);  /* actual vcpu cr3 */
>
> Any idea to rectify?  If my .config is required, I can post it.
>
> Thanks.
>
> Kindest regards,
> Giam Teck Choon
>
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