Re: [PATCH] tools lib traceevent: Add support for IP address formats

[David Ahern]

On 12/18/14 2:45 PM, Valdis.Kletnieks@xxxxxx wrote:
> On Thu, 18 Dec 2014 08:10:43 -0700, David Ahern said:
> > Adds helper for following kernel formats:
> >    %pi4 print an IPv4 address with leading zeros
> >    %pI4 print an IPv4 address without leading zeros
> >    %pi6 print an IPv6 address without colons
> >    %pI6 print an IPv6 address with colons
> >    %pI6c print an IPv6 address with colons
> >    %pISpc print an IP address from a sockaddr
>
> The description for %pI6C in the changelog doesn't match the code:
>
> > + * %pI6c  print an IPv6 address in compressed form with colons
>
> Threw me for a loop for a while trying to figure out how pI6 and pI6c were
> different, till I read the code...

Per Documentation/printk-formats.txt:

  %pI6    0001:0002:0003:0004:0005:0006:0007:0008
  %pi6    00010002000300040005000600070008
  %pI6c   1:2:3:4:5:6:7:8

  For printing IPv6 network-order 16-bit hex addresses. The 'I6' and 'i6'
  specifiers result in a printed address with ('I6') or without ('i6')
  colon-separators. Leading zeros are always used.

  The additional 'c' specifier can be used with the 'I' specifier to
  print a compressed IPv6 address as described by
        http://tools.ietf.org/html/rfc5952



I do see two mistakes in my patch -- use of 'c' and 'S' requires 'I'. 
After that the code that prints pI6c is a slightly modified version of 
what is in lib/vsprintf.c so the output between in-kernel tracing (cat 
trace_pipe) should match perf-script output. Compare 
ip6_compressed_string() in lib/vsprintf.c to print_ip6c_addr() in this 
patch.

Are you seeing something different?

David

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/