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Subject: Re: [PATCH] be2net: fix adapter->big_page_size miscaculation
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From: Qian Cai <cai@lca.pw>
Date: Fri, 12 Jul 2019 20:27:09 -0400

> Actually, GCC would consider it a const with -O2 optimized level because it found that it was never modified and it does not understand it is a module parameter. Considering the following code.
> 
> # cat const.c 
> #include <stdio.h>
> 
> static int a = 1;
> 
> int main(void)
> {
> 	if (__builtin_constant_p(a))
> 		printf("a is a const.\n");
> 
> 	return 0;
> }
> 
> # gcc -O2 const.c -o const

That's not a complete test case, and with a proper test case that
shows the externalization of the address of &a done by the module
parameter macros, gcc should not make this optimization or we should
define the module parameter macros in a way that makes this properly
clear to the compiler.

It makes no sense to hack around this locally in drivers and other
modules.

Thank you.