Re: [patch for 4.0] x86: silence warning in /dev/mem support

From: Ingo Molnar
Date: Mon Apr 20 2015 - 02:52:51 EST



* Pavel Machek <pavel@xxxxxx> wrote:

> Hi!
>
> > > CC arch/x86/mm/ioremap.o
> > > arch/x86/mm/ioremap.c: In function âxlate_dev_mem_ptrâ:
> > > arch/x86/mm/ioremap.c:363:10: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
> > > addr = (void *)((unsigned long)addr | (phys & ~PAGE_MASK));
> > > ^
> > > LD arch/x86/mm/built-in.o
> > >
> > > pavel@amd:/data/l/linux$ gcc --version
> > > gcc (Debian 4.9.2-10) 4.9.2
> >
> > So this code has not been changed for a year or so in theory, and I've
> > never seen this warning with GCC 4.9.1. I'm wondering how it
> > triggered. Could you send me your .config that triggers this?
>
> Config sent in private email. 32-bit kernel.

Ah, I see, the key is:

CONFIG_HIGHMEM64G=y

and neither x86 defconfig nor allyesconfig/allmodconfig selects
HIGHMEM64G apparently, so this was rarely triggered.

Thanks,

Ingo
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