On Tue, Jan 26, 2016 at 01:48:53PM +0100, Petr Mladek wrote:

On Tue 2016-01-26 11:50:25, Miroslav Benes wrote:

quoted

We still need Petr's patch from [1] to make livepatch work, right? Could 
you, please, add it to this patch set to make it self-sufficient?

It's Petr's patch, I don't want to decide how to best tackle this, see below.
I think Michael is already aware that it is needed, too.

quoted

Second, what is the situation with mcount prologue between gcc < 6 and 
gcc-6? Are there only 12 bytes in gcc-6 prologue? If yes, we need to 

Precisely, it's commit e95d0248daced44 (in http://repo.or.cz/official-gcc.git)
or svn trunk change 222352 "No need for -mprofile-kernel to save LR to stack."
It's efficient, I like it.

I am going to update the extra patch. There is an idea to detect the
offset during build by scrips/recordmcount. This tool looks for the
ftrace locations. The offset should always be a constant that depends
on the used architecture, compiler, and compiler flags.

My first idea was to check for compiler version defines, but some vendors
are rumoured to patch their compilers ;-)

The tool is called post build. We might need to pass the constant
as a symbol added to the binary. The tool already adds some symbols.

That's even better.
Thanks!
	Torsten