Messages in this thread | | | Date | Fri, 25 Jul 2008 13:43:26 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpu area |
| |
Mike Travis wrote: > Is this for the boot cpu (0), or for all cpus? For the boot cpu, I have > this now in arch/x86/kernel/setup_percpu.c: > > +#ifdef CONFIG_HAVE_ZERO_BASED_PER_CPU > + > +/* Initialize percpu offset for boot cpu (0) */ > +unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = { > + [0] = (unsigned long)__per_cpu_load > +}; > +#else > unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; > +#endif > > So this should apply as well to the xen startup? >
If it's just a static initialization, then it should be fine. But some equivalent of your head_64.S changes are needed to actually set things up?
>> xen_cpu_up() needs to do whatever initialization needed for a new cpu's >> percpu area (presumably whatever do_boot_cpu() does). >> >> > > Does the startup include executing arch/x86/kernel/head_64.S:startup_64() ? > I see arch/x86/xen/xen-head.S:startup_xen() so I'm guessing not? >
No, it doesn't. It bypasses all that startup code. Aside from the few instructions in xen-head.S, xen_start_kernel() is the first thing to get run.
But when bringing up a secondary cpu, where does the new percpu memory actually get allocated?
> For the real startup, I do the following two things. But I'm not comfortable > enough with xen to think I'll get it right putting this in xen-head.S. >
Yes, it needn't be in the asm code. I'll work out what to do. Looks like I just need to do an appropriate wrmsr(MSR_GS_BASE, ).
J
| |