On Fri, 19 Jan 2024 10:52:43 -0500 Steven Rostedt <[email protected]> wrote:
> On Fri, 19 Jan 2024 23:43:56 +0900 > Masami Hiramatsu (Google) <[email protected]> wrote: > > > Thanks for your proposal! > > > > Generically, I think this type of hack is not good for the tracing > > because there are already some ways to do that. e.g. > > - Use perf probe to specify dentry->name:string or file->name:string > > - Use BTF to specify in the same way (but only for function entry) > > And those are more obvious what it does. > > > > However, if this is implemented in more generic syntax, it will be > > acceptable. > > For example, type specifying with "arg1:printfmt(%pD)" will be > > more generic because it is apparently one of the printfmt and output > > string. Or, maybe we can just allow to use ":%pD" as a fetch type > > (start with '%' means the printfmt) > > Yes, I like this idea a lot. Please add the '%' keyword/token to change how > to display this in the print format. > > We may need to add more than one token though. Is that supported? > > $arg1:u32:%08x > > or that could also be: > > $arg1:%08x:u32 No, not yet. But I rather like comma separated. $arg1:u32,%08x Hm, this needs more changes, like a new type parser. And it will be a option of the default type. Thank you, > > That is, the order should not be important. > > Thoughts? > > -- Steve > > > > > > Also, could you update readme_msg[] in kernel/trace/trace.c if > > you add a type, and add a testcase of selftests/ftrace, for this > > feature? Documentation should also be updated with more syntax > > information. > -- Masami Hiramatsu (Google) <[email protected]>
