error: ‘MAP_SYNC’ undeclared and error: ‘MAP_SHARED_VALIDATE’

Question

After adding the flags MAP_SYNC | MAP_SHARED_VALIDATE I am getting error during compile time on mmap. I have included the header file <sys/mman.h>

I am using kernel version 5.6.8-1.el7.repo.x86_64 on centos-release-7-8.2003.0.el7.centos.x86_64

mmap(NULL, mapped_len, PROT_READ | PROT_WRITE, MAP_SYNC |MAP_SHARED_VALIDATE, uio_fd0, 2* 4096);

Also, are you developing a **kernel module** or a simple C program? — Marco Bonelli, May 22 '20 at 02:08
error: ‘MAP_SYNC’ undeclared (first use in this function) — Rahul K V, May 22 '20 at 02:09
i am trying to do persistant memory transaction after mapping with these fag to my pcie device bar — Rahul K V, May 22 '20 at 02:12
https://stackoverflow.com/questions/61936842/writing-to-persistent-memory-in-pcie — Rahul K V, May 22 '20 at 02:34
Ah, I see, that's my bad! I was looking at my system documentation and I have an older kernel version than 4.15. Sorry about that, those indeed seem to be valid flags. — Marco Bonelli, May 22 '20 at 02:40
It would be helpful to know which C library (and version) you are using, is it glibc? — Marco Bonelli, May 22 '20 at 02:42
That's the compiler version. I am talking about the *C library*, which one is it and which version? Post the output of `ldd --version`. In any case, have you tried to `#include `? If you have the headers for the current kernel installed you should be able to find those flags there. — Marco Bonelli, May 22 '20 at 03:02
Ah, that's the problem. glibc 2.17 is quite old (2012) while Linux 4.15 is much more recent (2018). I'll translate my previous comment into an answer. — Marco Bonelli, May 22 '20 at 03:19

score 1 · Answer 1 · answered May 22 '20 at 03:25

Your C library version is older than your current kernel version. The MAP_SYNC and MAP_SHARED_VALIDATE flags were introduced in Linux 4.15 (2018), while glibc 2.17 was released in 2012. If you have the kernel headers installed, you should be able to #include <linux/mman.h> for those values.

how to upgrade?

It's not that easy. You should be able to update using yum update, but chances are that your glibc package is already up to date and the CentOS maintainers are just not upgrading the package for your specific CentOS release. This question is better suited on SuperUser or on Unix&Linux SE, I would suggest you to ask there.

error: ‘MAP_SYNC’ undeclared and error: ‘MAP_SHARED_VALIDATE’

1 Answers1