Re: [Xen-devel] [PATCH 3/4] kexec/xen: use libxc to get location of crash notes

[Don Slutz <Don@xxxxxxxxxxxxxxx>]

On 02/21/13 12:57, David Vrabel wrote:
> From: David Vrabel <david.vrabel@xxxxxxxxxx>
>
> Use xc_kexec_get_range(KEXEC_RANGE_MA_CPU) instead of parsing
> /proc/iomem (which is only populated by non-upstream ("classic") Xen
> kernels).
>
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
> ---
>   kexec/crashdump-xen.c |   61 ++++++++++++++++++++++++++++---------------------
>   1 files changed, 35 insertions(+), 26 deletions(-)
>
> diff --git a/kexec/crashdump-xen.c b/kexec/crashdump-xen.c
> index ff4706c..13335a5 100644
> --- a/kexec/crashdump-xen.c
> +++ b/kexec/crashdump-xen.c
> @@ -163,42 +163,51 @@ unsigned long xen_architecture(struct crash_elf_info 
> *elf_info)
>         return machine;
>   }
>   
> -static int xen_crash_note_callback(void *UNUSED(data), int nr,
> -                                  char *UNUSED(str),
> -                                  unsigned long base,
> -                                  unsigned long length)
> -{
> -       struct crash_note_info *note = xen_phys_notes + nr;
> -
> -       note->base = base;
> -       note->length = length;
> -
> -       return 0;
> -}
> -
> +#ifdef HAVE_LIBXENCTRL
>   int xen_get_nr_phys_cpus(void)
>   {
> -       char *match = "Crash note\n";
> -       int cpus, n;
> +       xc_interface *xc;
> +       int cpu;
>   
>   	if (xen_phys_cpus)
>                 return xen_phys_cpus;
>   
> -	if ((cpus = kexec_iomem_for_each_line(match, NULL, NULL))) {
> -               n = sizeof(struct crash_note_info) * cpus;
> -               xen_phys_notes = malloc(n);
> -               if (!xen_phys_notes) {
> -                       fprintf(stderr, "failed to allocate xen_phys_notes.\n");
> +       xc = xc_interface_open(NULL, NULL, 0);
> +       if ( !xc ) {
> +               fprintf(stderr, "failed to open xen control interface.\n");
> +               return -1;
> +       }
> +
> +       for (cpu = 0;; cpu++) {
This code does work.  Not sure why you did not use xc_physinfo() to get 
the number of cpus that there is data for and remove the need for 
calling realloc.
> +               uint64_t size, start;
> +               int ret;
> +
> +               ret = xc_kexec_get_range(xc, KEXEC_RANGE_MA_CPU, cpu, &size, 
> &start);
> +               if (ret < 0)
> +                       break;
> +
> +               xen_phys_notes = realloc(xen_phys_notes,
> +                                        sizeof(*xen_phys_notes) * (cpu + 1));
> +               if (xen_phys_notes == NULL)
>                         return -1;
> -               }
> -               memset(xen_phys_notes, 0, n);
> -               kexec_iomem_for_each_line(match,
> -                                         xen_crash_note_callback, NULL);
> -               xen_phys_cpus = cpus;
> +
> +               xen_phys_notes[cpu].base = start;
> +               xen_phys_notes[cpu].length = size;
>         }
>   
> -	return cpus;
> +       xc_interface_close(xc);
> +
> +       xen_phys_cpus = cpu;
> +
> +       return cpu;
>   }
> +#else
> +int xen_get_nr_phys_cpus(void)
> +{
> +       return -1;
> +}
> +#endif
> +
>   
>   int xen_get_note(int cpu, uint64_t *addr, uint64_t *len)
>   {
   -Don Slutz

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