[Crash-utility] Re: [Patch] Fix dev -p command for systems with virtual devices

[Dave Anderson]

Rachita Kothiyal wrote:

> Hi Dave
>
> Running 'dev -p' command on PowerPC systems with virtual devices (ie
> no real PCI devices) fails with the following message:
>
> dev: invalid kernel virtual address: 98  type: "pci bus number"
>
> It should instead report that there are no _real_ PCI devices to list.
> The following patch addresses this issue. Currently it just prints a
> message letting the user know of the absence of pci devices, but it
> might be a good idea to list down the virtual devices present in the
> system in such cases. I am working on a patch for that too, probably
> will discuss that on another thread.
>
> Please provide your comments/suggestions.
>
> Thanks
> Rachita

Hi Rachita,

Yep -- in fact I see that the same thing happens on xen kernels
as well.  I'll test your patch out on a few other architectures, and
if all goes well, I'll queue it for the next release.

Thanks again,
  Dave


>
>
>  On PowerPC machines configured with virtual devices(VIO) it is possible
>  that there are no _real_ PCI devices. Hence it is reasonable that 'dev -p'
>  would not list anything. This patch identifies such cases and displays a
>  message appropriately.
>
> Signed-off-by: Rachita Kothiyal <rachita at in.ibm.com>
> ---
>
>  dev.c |   30 +++++++++++++++++++++++++++---
>  1 files changed, 27 insertions(+), 3 deletions(-)
>
> diff -puN dev.c~fix-vio-pci-device dev.c
> --- crash-4.0-3.9/dev.c~fix-vio-pci-device      2006-12-22 13:32:02.737262096 +0530
> +++ crash-4.0-3.9-rachita/dev.c 2006-12-22 13:48:44.984897296 +0530
> @@ -1955,13 +1955,11 @@ do_pci(void)
>         unsigned int      class;
>         unsigned short    device, vendor;
>         unsigned char     busno;
> -       ulong             *devlist, bus, devfn, tmp;
> +       ulong             *devlist, bus, devfn, tmp, prev, next;
>         char              buf1[BUFSIZE];
>         char              buf2[BUFSIZE];
>         char              buf3[BUFSIZE];
>
> -       fprintf(fp, "%s BU:SL.FN CLASS: VENDOR-DEVICE\n",
> -               mkstring(buf1, VADDR_PRLEN, CENTER|LJUST, "PCI_DEV"));
>
>         BZERO(&pcilist_data, sizeof(struct list_data));
>
> @@ -1972,11 +1970,34 @@ do_pci(void)
>                          FAULT_ON_ERROR);
>                  pcilist_data.end = symbol_value("pci_devices");
>                  pcilist_data.list_head_offset = OFFSET(pci_dev_global_list);
> +               readmem(symbol_value("pci_devices") + OFFSET(list_head_prev),
> +                       KVADDR, &prev, sizeof(void *), "list head prev",
> +                       FAULT_ON_ERROR);
> +                /*
> +                * Check if this system does not have any PCI devices.
> +                * Possible on PowerPC machines with VIO configured.
> +                */
> +               if ((pcilist_data.start == pcilist_data.end) &&
> +                  (prev == pcilist_data.end)) {
> +                       fprintf(fp, "No PCI devices found on this system.\n");
> +                       return;
> +               }
>
>         } else {
>                 get_symbol_data("pci_devices", sizeof(void *),
>                                 &pcilist_data.start);
>                 pcilist_data.member_offset = OFFSET(pci_dev_next);
> +                /*
> +                * Check if this system does not have any PCI devices.
> +                * Possible on PowerPC machines with VIO configured.
> +                */
> +               readmem(pcilist_data.start + pcilist_data.member_offset,
> +                       KVADDR, &next, sizeof(void *), "pci dev next",
> +                       FAULT_ON_ERROR);
> +               if (!next) {
> +                       fprintf(fp, "No PCI devices found on this system.\n");
> +                       return;
> +               }
>         }
>
>         hq_open();
> @@ -1985,6 +2006,9 @@ do_pci(void)
>         devcnt = retrieve_list(devlist, devcnt);
>         hq_close();
>
> +       fprintf(fp, "%s BU:SL.FN CLASS: VENDOR-DEVICE\n",
> +               mkstring(buf1, VADDR_PRLEN, CENTER|LJUST, "PCI_DEV"));
> +
>         for (i = 0; i < devcnt; i++) {
>
>                 /*
> _