[lkml]   [2007]   [Jun]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Userspace compiler support of "long long"
On Jun 28, 2007, at 08:08:03, Jakub Jelinek wrote:
> On Thu, Jun 28, 2007 at 07:53:51AM -0400, Kyle Moffett wrote:
>> Oh, ok, that makes it even easier to say this with certainty:
>> Changing the other 64-bit archs to use "long long" for their 64-
>> bit numbers will not cause additional warnings. I'm also almost
>> certain there are no architectures which use "long long" for 128-
>> bit integers. (Moreover, I can't find hardly anything which does
>> 128-bit integers at all).
> unsigned long and unsigned long long have the same size, precision
> and alignment on all LP64 arches, that's true. But they have
> different ranks and more importantly they mangle differently in C+
> +. So, whether some user exposed type uses unsigned long or
> unsigned long long is part of the ABI, whether that's size_t,
> uintptr_t, uint64_t, u_int64_t or any other type, you can't change
> it without breaking the ABI.

That sounds *extraordinarily* broken. Hopefully this would *not*
affect the type of a function which is passed a C "struct" containing
the "long long", right?

Hmm, I guess the question is: Do we support people directly passing
__u64 to C++ functions in userspace? I could understand, perhaps,
passing around structures defined in the kernel headers, but
certainly not the kernel-internal types. The only reason we even
export those is so we can have a private set of bit-size-defined
types with which to define kernel ABI structures.

Kyle Moffett

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-06-28 16:35    [W:0.063 / U:25.084 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site