[Crash-utility] [PATCH] Rename kernel log buffer from 'log' to 'printk_log'

[Dave Anderson]

----- Original Message -----
> Hi
> 
> On Tue, Aug 13, 2013 at 12:43 PM, Anatol Pomozov
> <anatol.pomozov at gmail.com> wrote:
> > In kernel 3.11 it was renamed to printk_log.
> > See kernel commit 62e32ac3505a0cab1c5ef8ea2c0eab3b26ed855f
> >
> > Tested: can run 'log' command for 3.11-rc4 and 3.3 kernel dumps
> > ---
> >  kernel.c | 25 ++++++++++++++++---------
> >  1 file changed, 16 insertions(+), 9 deletions(-)
> >
> > diff --git a/kernel.c b/kernel.c
> > index 73c2cc6..6cc4954 100755
> > --- a/kernel.c
> > +++ b/kernel.c
> > @@ -4428,17 +4428,24 @@ dump_variable_length_record_log(int msg_flags)
> >  {
> >         uint32_t idx, log_first_idx, log_next_idx, log_buf_len;
> >         ulong log_buf;
> > -       char *logptr, *logbuf;
> > +       char *logptr, *logbuf, *log_struct_name = "printk_log";
> >
> >         if (INVALID_SIZE(log)) {
> > -               STRUCT_SIZE_INIT(log, "log");
> > -               MEMBER_OFFSET_INIT(log_ts_nsec, "log", "ts_nsec");
> > -               MEMBER_OFFSET_INIT(log_len, "log", "len");
> > -               MEMBER_OFFSET_INIT(log_text_len, "log", "text_len");
> > -               MEMBER_OFFSET_INIT(log_dict_len, "log", "dict_len");
> > -               MEMBER_OFFSET_INIT(log_level, "log", "level");
> > -               MEMBER_SIZE_INIT(log_level, "log", "level");
> > -               MEMBER_OFFSET_INIT(log_flags_level, "log", "flags_level");
> > +               STRUCT_SIZE_INIT(log, log_struct_name);
> > +               if (INVALID_SIZE(log)) {
> 
> It might be better to use kernel_symbol_exists() to find whether it is
> new or old style log.
> 
> > +                       // It looks like a pre 3.11 kernel.
> > +                       // See commit 62e32ac3505a0cab that changed
> > structure name
> > +                       // log -> printk_log
> > +                       log_struct_name = "log";
> > +                       STRUCT_SIZE_INIT(log, log_struct_name);
> > +               }
> > +               MEMBER_OFFSET_INIT(log_ts_nsec, log_struct_name,
> > "ts_nsec");
> > +               MEMBER_OFFSET_INIT(log_len, log_struct_name, "len");
> > +               MEMBER_OFFSET_INIT(log_text_len, log_struct_name,
> > "text_len");
> > +               MEMBER_OFFSET_INIT(log_dict_len, log_struct_name,
> > "dict_len");
> > +               MEMBER_OFFSET_INIT(log_level, log_struct_name, "level");
> > +               MEMBER_SIZE_INIT(log_level, log_struct_name, "level");
> > +               MEMBER_OFFSET_INIT(log_flags_level, log_struct_name,
> > "flags_level");
> >
> >                 /*
> >                  * If things change, don't kill a dumpfile session
> > --
> > 1.8.3
> >
> 

Hello Anatol,

Sorry for the delay -- I'm still recovering from a 2-week vacation, and
I was planning to get around to this tomorrow (hopefully).

Anyway, the kernel_symbol_exists() function only works for kernel symbols, 
not for data structures.  And I don't think the symbol name of the actual
buffer has changed, correct?

Probably the best way would be to: 

     if (STRUCT_EXISTS("printk_log")) {
           <new way>
     } else {
           <old way>
     }

Can you post another patch?

Thanks,
  Dave