Re: [Qemu-trivial] [Qemu-devel] [PATCH] configure: Make epoll_create1 test work around SPARC glibc bug

[Blue Swirl <blauwirbel@gmail.com>]

On Wed, Apr 20, 2011 at 9:53 AM, Peter Maydell <peter.maydell@linaro.org> wrote:
> On 19 April 2011 21:36, Blue Swirl <blauwirbel@gmail.com> wrote:
>> Sorry, I just picked a define without much thought. A more specific
>> one would be flags parameter of epoll_create1(), like EPOLL_CLOEXEC or
>> EPOLL_NONBLOCK. We don't use them now since the target system call
>> argument is passed untranslated to host, but that is actually not
>> correct, since the bit definitions could be different. So checking for
>> one of those should be OK.
>
> Unfortunately the header file on the system in question defines
> both EPOLL_CLOEXEC and EPOLL_NONBLOCK even though it doesn't
> prototype epoll_create1(). So this idea won't work.
> The bug we are effectively trying to work around is the one fixed
> by this libc patch:
> http://sourceware.org/ml/libc-alpha/2010-08/msg00128.html
>
> The only problem with the header is that it doesn't declare the
> function, so the only way to detect it is to do something that
> will fail if the function isn't declared, like compiling -Werror.

This also fails without -Werror:
#include <sys/epoll.h>

int main(void)
{
    epoll_create1;
    return 0;
}