Re: [PATCH 4.19 5/6] ARM: 8788/1: ftrace: remove old mcount support

[Stefan Agner]

On 2021-12-20 11:57, Greg KH wrote:
> On Fri, Dec 17, 2021 at 03:41:18PM +0100, Anders Roxell wrote:
>> From: Stefan Agner <stefan@xxxxxxxx>
>>
>> commit d3c61619568c88d48eccd5e74b4f84faa1440652 upstream.
>>
>> Commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6")
>> raised the minimum GCC version to 4.6. Old mcount is only required for
>> GCC versions older than 4.4.0. Hence old mcount support can be dropped
>> too.
>>
>> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
>> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
>> Signed-off-by: Anders Roxell <anders.roxell@xxxxxxxxxx>
> 
> Why is this needed for clang builds in 4.19?

As far as I remember, Clang tripped over this part:

-#ifndef CONFIG_OLD_MCOUNT
-#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
-#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than
4.4.0.
-#endif
-#endif

Since mcount support wasn't required upstream at that point, instead of
fixing it for Clang I just removed it.

--
Stefan