Re: [PATCH] staging: Disable lustre file system for MIPS, SH, and XTENSA

[Geert Uytterhoeven]

On Mon, Sep 9, 2013 at 10:06 PM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>> [*] Why does m68k allmodconfig still succeed on kissb???
>>     It does fail for me, as m68k's copy_from_user_page() calls
>>     flush_icache_user_range(), which is not exported.
>>
> I don't see a build failure in m68k:allmodconfig either.
>
> flush_icache_user_range() is called from copy_to_user_page(), not from
> copy_from_user_page(). copy_from_user_page() calls flush_cache_page()
> which calls __flush_cache_030(). The first is inline, the second is
> assembler, so I would expect it to work. Which doesn't answer
> the question why it fails for you.

Sorry, I meant copy_to_user_page().

I tried with 2.6.3 from crosstool, and it succeeded, too.

Turns out cfs_access_process_vm() is called with write=0 only.
Gcc 2.6.3 optimizes away the write != 0 branch (which calls copy_to_user_page()
and thus flush_icache_user_range()), while gcc 4.1.2 doesn't do that.
Mystery solved.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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