Re: [PATCH v2 2/2] tracing: Use seq_buf_hex_dump() to dump buffers

[Piotr Maziarz]

On 2019-11-26 20:51, Steven Rostedt wrote:
> On Tue, 26 Nov 2019 15:53:26 +0100
> Piotr Maziarz <piotrx.maziarz@xxxxxxxxxxxxxxx> wrote:
> > Hello Steven,
> >
> > I'm writing handle in event-parse and I came across some technical
> > problems. I have an event which print function looks like that:
> > TP_printk("%s",
> > 	  __print_hex_dump("", DUMP_PREFIX_OFFSET, 16, 4,
> > 			   __get_dynamic_array(buf),
> > 			   __get_dynamic_array_len(buf), false))
> > It works properly when printing events to debugfs.
> > I'm testing my implementation with trace-cmd and it has problem with
> > parsing DUMP_PREFIX_OFFSET and false (I'm using
> > alloc_and_process_delim()). Instead of having numerical values
> > tep_print_args are of type TEP_PRINT_ATOM and have char array
> > "DUMP_PREFIX_OFFSET" or "true".
> > Am I doing something incorrect? Parsing it this way is problematic
> > because instead of false someone may use 0 or logic expression. And
> > writing it to support all possible scenarios may be tedious and prone to
> > errors.
>
> You can force the enum to be a number by including the following in the
> trace event header:
>
> TRACE_DEFINE_ENUM(DUMP_PREFIX_OFFSET);
> TRACE_DEFINE_ENUM(DUMP_PREFIX_ADDRESS);
> TRACE_DEFINE_ENUM(DUMP_PREFIX_NONE);
>
> and the format files will convert these to their actual numbers when
> displaying it to user space.
>
> -- Steve
Thanks, that's what I was looking for.

Best regards,
Piotr Maziarz