Re: [Xen-devel] [PATCH] Add device-path command.

["Daniel P. Berrange" <berrange@xxxxxxxxxx>]

On Mon, Apr 06, 2009 at 05:03:37PM +0900, Yuji Shimada wrote:
> This patch adds device-path command that converts SBDF into device
> path.

[snip]

> diff -r 5a60eb7fad79 tools/misc/device-path
> --- /dev/null Thu Jan 01 00:00:00 1970 +0000
> +++ b/tools/misc/device-path  Mon Apr 06 16:30:11 2009 +0900


[snip]

> +SYSFS_ACPI_DEVS_PATH = '/firmware/acpi/namespace/ACPI/_SB'
> +
> +def find_hid_uid(dom, b, d, f):
> +    sb_path = find_sysfs_mnt() + SYSFS_ACPI_DEVS_PATH
> +    obj_list = os.listdir(sb_path)
> +    for obj in obj_list:
> +        obj_path = sb_path + '/' + obj.strip() + '/'
> +        if os.path.exists(obj_path + 'seg') and \
> +            os.path.exists(obj_path + 'bbn'):
> +            seg = open(obj_path + 'seg').read()
> +            bbn = open(obj_path + 'bbn').read()
> +            if int(seg) == dom and int(bbn) == b:
> +                hid = open(obj_path + 'hid').read()
> +                if os.path.exists(obj_path + 'uid') is False:
> +                    path_str = hid.strip()
> +                else:
> +                    uid = open(obj_path + 'uid').read()
> +                    path_str = hid.strip() + ':' + uid.strip()
> +                return path_str
> +    return None

I don't know how critical this piece of code is to the overall functionality
in this tool, but be warned that the path being used here was removed from
sysfs in upstream kernel quite a while ago

To quote an old copy of  Documentation/feature-removal-schedule.txt

  What:  /sys/firmware/acpi/namespace
  When:  2.6.21
  Why:   The ACPI namespace is effectively the symbol list for
         the BIOS.  The device names are completely arbitrary
         and have no place being exposed to user-space.
  
         For those interested in the BIOS ACPI namespace,
         the BIOS can be extracted and disassembled with acpidump
         and iasl as documented in the pmtools package here:
         http://ftp.kernel.org/pub/linux/kernel/people/lenb/acpi/utils

Regards,
Daniel
-- 
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