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Subject: Re: [PATCH 5/7] printk: Make %pS and friends print module build ID
To:     Stephen Boyd <swboyd@chromium.org>,
        Matthew Wilcox <willy@infradead.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, Jiri Olsa <jolsa@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Jessica Yu <jeyu@kernel.org>,
        Evan Green <evgreen@chromium.org>,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        linux-doc@vger.kernel.org
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 <20210304170052.GK2723601@casper.infradead.org>
 <161488534185.1478170.10285681551102444519@swboyd.mtv.corp.google.com>
From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
Message-ID: <95e58426-c7ab-6ba5-17ea-392754899959@rasmusvillemoes.dk>
Date:   Fri, 5 Mar 2021 00:11:47 +0100
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On 04/03/2021 20.15, Stephen Boyd wrote:
> Quoting Matthew Wilcox (2021-03-04 09:00:52)
>> On Mon, Mar 01, 2021 at 09:47:47AM -0800, Stephen Boyd wrote:
>>> Example:
>>>
>>>  WARNING: CPU: 4 PID: 3255 at drivers/misc/lkdtm/bugs.c:83 lkdtm_WARNING+0x28/0x30 [lkdtm] (ed5019fdf5e53be37cb1ba7899292d7e143b259e)
>>
>> Would the first 12 characters instead of all 40 make it more palatable
>> without reducing its utility?
> 
> I can't seem to request debuginfo from debuginfod without the full 40
> characters. It's not a git sha1 hash. 
> 
>> And I feel it should be within the [], so maybe this:
>>
>> WARNING: CPU: 4 PID: 3255 at drivers/misc/lkdtm/bugs.c:83 lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e5]
>>
> 
> Sure I could put the hex numbers inside the brackets. I suspect changing
> %pS or updating the "Modules linked in:" line isn't going to be
> palatable. I've decided to introduce another printk format %pT to print
> the stacktrace 

Can you avoid claiming a new "top-level" %p modifier? Isn't it better to
add a new flag to '%pS', say '%pSb' to include build-id?

Rasmus