RE: [RFC] ARC: initial ftrace support

[Alexey Brodkin]

Hi Claus,

> -----Original Message-----
> From: linux-snps-arc <linux-snps-arc-bounces@xxxxxxxxxxxxxxxxxxx> On Behalf Of Claudiu Zissulescu
> Ianculescu
> Sent: Thursday, April 2, 2020 11:10 AM
> To: Vineet Gupta <vgupta@xxxxxxxxxxxx>
> Cc: Alexey Brodkin <abrodkin@xxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; Steven Rostedt
> <rostedt@xxxxxxxxxxx>; Ingo Molnar <mingo@xxxxxxxxxx>; linux-snps-arc@xxxxxxxxxxxxxxxxxxx; Eugeniy
> Paltsev <paltsev@xxxxxxxxxxxx>
> Subject: Re: [RFC] ARC: initial ftrace support
> 
> Hi,
> 
> ARC-gcc has two modes to call the mcount routines. When using elf32
> configuration, the toolchain is set to use newlib mcount. When
> configured for linux, gcc toolchain is using a library call to _mcall
> (single underscore)  having blink as input argument.
> So, using the proper linux toolchain, your patch should work.


Is there a chance to switch to Linux-style mcount in Elf32 toolchain with a command-line
option?

Otherwise I guess we'll need to implement some warning which explicitly says why Elf32
toolchain is not usable for building the Linux kernel... at least in case with ftrace enabled.

-Alexey