On Tue, Sep 25, 2012 at 9:43 PM, Al Viro <v...@zeniv.linux.org.uk> wrote:
> On Tue, Sep 25, 2012 at 12:20:55PM -0700, Linus Torvalds wrote:
>> IOW, this part of the patch:
>>
>> - c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS) -include user.h
>> $(CFLAGS_$(basetarget).o)
>> + c_flags = -Wp,-MD,$(depfile) $(USER_CFLAGS) -include
>> $(srctree)/include/linux/kern_levels.h -include user.h
>> $(CFLAGS_$(basetarget).o)
>>
>> just makes me go want to puke. The user.h file already has other
>> #include's in it, so I really don't see why you create this insane
>> special case.
>>
>> And why does UM have those "UM_KERN_XYZ" defines in the first place?
>> Why isn't it just using KERN_XYZ directly? Is it because kern_levels.h
>> didn't use to exist, so it was some kind of "let's create our own that
>> we can hide in our special headers".
>
> Because user.h is included *without* kernel headers in include path.
Indeed.
> It's for the stuff that is compiled with host libc headers. Keep in
> mind that UML talks to libc like normal architecture would talk to
> hardware. IOW, analogs of asm glue are in (host) userland C. And
> they need libc headers instead of the kernel ones. That's what that
> USER_OBJ thing is about. Kernel-side constants, etc. are delivered
> to that sucker using the same mechanism we normally use to give them
> to assembler - asm-offsets.c. And here, of course, slapping ifndef
> __ASSEMBLER__ around the tricky bits will not work - the header itself
> is just fine, but getting kernel headers in the search path really
> isn't.
>
> I agree that proposed solution is ugly. What we can do is copy
> the damn header into include/generated and #include <generated/kern_levels.h>
> from user.h. And kill UM_KERN_... stuff. Objections?
My first submission had "We may convert all UM_KERN_* users to KERN_*
and drop the extra defines?" as a suggestion, but so far I haven't found time
to implement that...
Still, no one came up with a better patch, and this is a regression.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
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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