Hi
On Wed, Jul 29, 2015 at 6:19 PM, Paul Gortmaker
<paul.gortmaker@xxxxxxxxxxxxx> wrote:
> Hi David,
>
> Does it make sense to build this sample when cross compiling?
>
> The reason I ask is that it has been breaking the linux-next build of
> allmodconfig for a while now, with:
>
> HOSTCC samples/kdbus/kdbus-workers
> samples/kdbus/kdbus-workers.c: In function ‘prime_new’:
> samples/kdbus/kdbus-workers.c:934:18: error: ‘__NR_memfd_create’ undeclared (first use in this function)
> p->fd = syscall(__NR_memfd_create, "prime-area", MFD_CLOEXEC);
> ^
> samples/kdbus/kdbus-workers.c:934:18: note: each undeclared identifier is reported only once for each function it appears in
> scripts/Makefile.host:91: recipe for target 'samples/kdbus/kdbus-workers' failed
> make[2]: *** [samples/kdbus/kdbus-workers] Error 1
mips does have this syscall, so I assume the problem is out-of-date
kernel headers. You can fix this by running:
$ make headers_install
This will put the sanitized headers in your local kernel tree
"./usr/". This is preferred over "/usr" as include path for the kernel
examples, hence, everything should work fine then.
The kernel samples/ directory is explicitly used for example programs
for the kernel. Hence, I think it is quite fine to use new kernel
features. Same applies to the selftests.
I'd be fine making kdbus-workers a no-op program if __NR_memfd_create
is not defined. But I'm not really sure that fixes real problems. I
mean, new samples and selftests will be added by other subsystems and
those might as well require new kernel headers.
Thanks
David
