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truf
Asked: 2021-12-10 02:34:16 +0800 CST

Building a linux module - sys/time.h: No such file or directory

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I'm trying to build an old linux driver in my system (Kubuntu 21.10) with make -C ....
The driver is declaring static struct timeval frame_timestamp;

If I try to build it with something like

make -C /lib/modules/`uname -r`/build M=`pwd` V=1  modules

I'm getting ... has an incomplete type ‘struct timeval’ error and some other related errors.
So I believe I must include sys/time.h with #include <sys/time.h> into the code.
But in this case I'm getting fatal error: sys/time.h: No such file or directory. And I cant't find a way to resolve this. (The code already had some includes but none from sys/, they are all from linux/ and media/)

I ended up with a following Makefile:

obj-m := mydriver.o
KDIR := /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)

default:
    $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) M=$(PWD) V=1 modules

The KDIR resolves into /lib/modules/5.13.0-21-generic/build which links to /usr/src/linux-headers-5.13.0-21-generic. There is no sys/time.h.

locate sys/time.h returns:

/usr/include/i386-linux-gnu/sys/time.h
/usr/include/sys/time.h
/usr/include/x86_64-linux-gnu/sys/time.h

which belongs to libc6-dev and libc6-dev-i386:.
dpkg -l *5.13.0-21* gives:

ii  linux-headers-5.13.0-21                5.13.0-21.21 all          Header files related to Linux kernel version 5.13.0
ii  linux-headers-5.13.0-21-generic        5.13.0-21.21 amd64        Linux kernel headers for version 5.13.0 on 64 bit x86 SMP
ii  linux-image-5.13.0-21-generic          5.13.0-21.21 amd64        Signed kernel image generic
un  linux-image-unsigned-5.13.0-21-generic <нет>        <нет>        (описание недоступно)
ii  linux-modules-5.13.0-21-generic        5.13.0-21.21 amd64        Linux kernel extra modules for version 5.13.0 on 64 bit x86 >
ii  linux-modules-extra-5.13.0-21-generic  5.13.0-21.21 amd64        Linux kernel extra modules for version 5.13.0 on 64 bit x86

I was trying to hardcode -I /usr/include/x86_64-linux-gnu/ into make -C - this has no effect.
I also tried to download a vanilla kernel from kernel.org: https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.13.tar.xz and hardcode it as KDIR - that doesn't help and it's not containing sys/time.h either.

The question is: how to force my module build process to see the sys/time.h?
Does linux module allowed to link to libc? If it's not a part of the kernel, how to make it available for module buildprocess?

kernel

1 Answers

  1. Ok, it seems one can't use sys/time.h in kernel module.
    I have taken a look at definition of struct v4l2_buffer in linux/videodev2.h where the struct timeval is supposed to be used by the driver to initialize its timestamp field and found there:

    truct v4l2_buffer {
    __u32           index;
    __u32           type;
    __u32           bytesused;
    __u32           flags;
    __u32           field;
#ifdef __KERNEL__
    struct __kernel_v4l2_timeval timestamp;
#else
    struct timeval      timestamp;
#endif
    struct v4l2_timecode    timecode;
....

    The __KERNEL__ is defined automatically somewhere in make -C process, so up-to-date kernel expects to get __kernel_v4l2_timeval. Replacing struct timeval with struct __kernel_v4l2_timeval among with some other tricks allowed me to compile this old driver.

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