[Xen-devel] Re: [PATCH] kexec/kdump: statically allocate xen_phys_cpus

[Horms <horms@xxxxxxxxxxxx>]

On Thu, Sep 20, 2007 at 06:38:08PM +0900, Horms wrote:
> On Thu, Sep 20, 2007 at 10:15:01AM +0100, Ian Campbell wrote:
> > You posted to xen-ia64-devel & xen-ia64 (deleted the wrong word?)
> > rather than xen-devel so I added that to the CC.
> 
> Thanks. I've trimmed xen-ia64
> 
> > On Thu, 2007-09-20 at 13:38 +0900, Simon Horman wrote:
> > > On IA64 alloc_bootmem_low() can't be called this early.
> > > 
> > > Before alloc_bootmem_low() can be called init_bootmem(), which is called 
> > > in
> > > find_memory(). However xen_machine_kexec_setup_resources() is indirectly
> > > called earlier on in find_memory().
> > 
> > Can the root cause not be fixed i.e. allow the call to
> > alloc_bootmem_low() earlier or move the call to
> > xen_machine_kexec_setup_resource() later, rather than papering over it
> > by making a potentially large static array?
> 
> The last time that I looked, it seemed to be quite painful.
> But I'll look over it again, I agree that the static array
> should be avoided if possible.

Hi Ian,

I have found that by changing things around a bit so that
xen_machine_kexec_setup_resource() is called directly in
find_memory() after init_bootmem() the problem that I was
seeing goes away without requiring static allocation.

I'm dropping this patch accordingly.

> > > Cc: Ian Campbell <ian.campbell@xxxxxxxxxxxxx>
> > > Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
> > > 
> > > ---
> > > Date: Thu, 20 Sep 2007 13:37:10 +0900
> > > From: Simon Horman <horms@xxxxxxxxxxxx>
> > > 
> > > Posted to xen-devel as it changes common code.
> > > As suggested by Alex Williamson.
> > > 
> > > Index: x/drivers/xen/core/machine_kexec.c
> > > ===================================================================
> > > --- x/drivers/xen/core/machine_kexec.c    2007-05-11 18:19:20.000000000 
> > > +0900
> > > +++ x/drivers/xen/core/machine_kexec.c    2007-05-14 19:18:03.000000000 
> > > +0900
> > > @@ -13,7 +13,7 @@ extern void machine_kexec_setup_load_arg
> > >  
> > >  static int __initdata xen_max_nr_phys_cpus;
> > >  static struct resource xen_hypervisor_res;
> > > -static struct resource *xen_phys_cpus;
> > > +static struct resource xen_phys_cpus[NR_CPUS];
> > >  
> > >  void __init xen_machine_kexec_setup_resources(void)
> > >  {
> > > @@ -42,11 +42,6 @@ void xen_machine_kexec_setup_resources(v
> > >  
> > >   xen_max_nr_phys_cpus = k;
> > >  
> > > - /* allocate xen_phys_cpus */
> > > -
> > > - xen_phys_cpus = alloc_bootmem_low(k * sizeof(struct resource));
> > > - BUG_ON(xen_phys_cpus == NULL);
> > > -
> > >   /* fill in xen_phys_cpus with per-cpu crash note information */
> > >  
> > >   for (k = 0; k < xen_max_nr_phys_cpus; k++) {
> 
> -- 
> Horms
>   H: http://www.vergenet.net/~horms/
>   W: http://www.valinux.co.jp/en/
> 

-- 
Horms
  H: http://www.vergenet.net/~horms/
  W: http://www.valinux.co.jp/en/


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