Messages in this thread | | | Date | Sat, 28 Dec 2013 11:25:09 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] lib/vsprintf: add %pT[C012] format specifier |
| |
On Sat, 28 Dec 2013 19:57:50 +0100 Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > If we introduce a character which compiler does not know that follows the % > > character, compiler would be confused when checking type of corresponding > > argument. > > > >> I wonder if there's some way in which we can invent a vsprintf token > >> which means "insert corrent->comm here" and which doesn't require that > >> the caller pass in the additional argument? > > > > Therefore, if we want to omit passing corresponding argument, we should not > > introduce new character which compiler does not know that follows the % > > character. > > > > Also, % is the only character which everybody knows that it is reserved for the > > beginning of format specifier and %% is the only characters which everybody > > knows that it is reserved for literal % character. > > > > Therefore, what we could do for printing current thread's attributes would be > > either reserve a new character and add EXTENSION like > > > > pr_warn("$comm$: hair on fire\n"); > > pr_warn("Process $pid$: hair on fire\n"); > > > > or add EXTENSION after the %% characters like > > > > pr_warn("%%comm%%: hair on fire\n"); > > pr_warn("Process %%pid%%: hair on fire\n"); > > ESC sequences? So far printk() doesn't parse them (a bit unfortunate, as I > always liked the idea of printing error messages in red, warnings in yellow, > etc.). > > Is any of the "\x" (backslash + character) unused and thus available?
I guess control characters would work.
#define PRINTK_COMM "\001" #define PRINTK_PID "\002" #define PRINTK_TASK_ID "\003" /* "comm:pid" */
printk(PRINTK_TASK_ID ": hair on fire\n");
It's certainly compact. I doubt if there's any existing code which deliberately prints control chars?
| |