On Wed, Feb 28, 2024 at 03:00:01PM +0100, Geert Uytterhoeven wrote:
> Hi all,
>
> When printk-indexing is enabled, each printk() invocation emits a
> pi_entry structure, containing the format string and other information
> related to its location in the kernel sources. This is even true when
> the printk() is protected by an always-false check, as is typically the
> case for debug messages: while the actual code to print the message is
> optimized out by the compiler, the pi_entry structure is still emitted.
> Hence when debugging is disabled, this leads to the inclusion in the
> index of lots of printk formats that cannot be emitted by the current
> kernel.
>
> This series fixes that for the common debug helpers under include/.
> It reduces the size of an arm64 defconfig kernel with
> CONFIG_PRINTK_INDEX=y by ca. 1.5 MiB, or 28% of the overhead of
> enabling CONFIG_PRINTK_INDEX=y.
>
> Notes:
> - netdev_(v)dbg() and netif_(v)dbg() are not affected, as
> net{dev,if}_printk() do not implement printk-indexing, except
> for the single global internal instance of __netdev_printk().
> - This series fixes only debug code in global header files under
> include/. There are more cases to fix in subsystem-specific header
> files and in sources files.
The whole series makes a lot of sense and gives a good examples for above
mentioned subsystem specific code on how to do it in a better way.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
--
With Best Regards,
Andy Shevchenko
