Messages in this thread | | | From | Kyle Moffett <> | Subject | Re: [RFC][PATCH 1/2] Create initial kernel ABI header infrastructure | Date | Sun, 26 Mar 2006 07:50:28 -0500 |
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On Mar 26, 2006, at 07:32:31, Arjan van de Ven wrote: > On Sun, 2006-03-26 at 06:54 -0500, Kyle Moffett wrote: >> Create initial kernel ABI header infrastructure > > it's nice that you picked this one; > for this you want an arch-generic/stddef32.h and stddef64.h > > and have arch-foo just only include the proper generic one..
I plan to add a lot of other definitions to this file later on. For example different architectures have different notions of what a __kernel_ino_t is (unsigned int versus unsigned long). I may rename this file as types.h, but from looking through the code I figure I'll have enough general purpose declarations about "This architecture has blah" that a separate stddef.h file will be worth it.
> (and... why do you prefix these with _KABI? that's a mistake imo. > Don't bother with that. Really. Either these need exporting to > userspace, but then either use __ as prefix or don't use a prefix. > But KABI.. No.)
According to the various standards all symbols beginning with __ are reserved for "The Implementation", including the compiler, the standard library, the kernel, etc. In order to avoid clashing with any/all of those, I picked the __KABI_ and __kabi_ prefixes for uniqueness. In theory I could just use __, but there are problems with that too. For example, note how the current compiler.h files redefine __always_inline to mean something kinda different. The GCC manual says we should be able to write this:
inline __attribute__((__always_inline)) int increment(int x) { return x+1; }
Except when compiling the kernel headers turn that into this (which obviously doesn't compile): inline __attribute__((__attribute__((always_inline)))) int increment (int x) { return x+1; }
As a result, I kinda want to stay away from anything that remotely looks like a conflicting namespace. Using such a unique namespace means we can also safely do this if necessary (Since you can't "typedef struct foo struct bar"):
kabi/foo.h: struct __kabi_foo { int x; int y; };
linux/foo.h: #define __kabi_foo foo #include <kabi/foo.h>
drivers/foo/foo.h: #include <linux/foo.h> void func() { struct foo = { .x = 1, .y = 2 }; }
Cheers, Kyle Moffett
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