From:   "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To:     Khadija Kamran <kamrankhadijadj@gmail.com>
Cc:     outreachy@lists.linux.dev,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5] staging: axis-fifo: initialize timeouts in probe only
Date:   Mon, 20 Mar 2023 15:09:57 +0100
Message-ID: <1788637.Zkmt1EvEu4@suse>
In-Reply-To: <ZBf2fNF4AC3ovR1B@khadija-virtual-machine>
References: <ZBMR4s8xyHGqMm72@khadija-virtual-machine> <2599595.k3LOHGUjKi@suse>
 <ZBf2fNF4AC3ovR1B@khadija-virtual-machine>
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On luned=EC 20 marzo 2023 07:00:28 CET Khadija Kamran wrote:
> On Thu, Mar 16, 2023 at 09:07:09PM +0100, Fabio M. De Francesco wrote:
> > On gioved=EC 16 marzo 2023 19:35:09 CET Khadija Kamran wrote:
> > > On Thu, Mar 16, 2023 at 05:17:47PM +0100, Fabio M. De Francesco wrote:
> > > > On gioved=EC 16 marzo 2023 16:09:08 CET Khadija Kamran wrote:
> > [snip]
> >=20
> > > Hey Fabio!
> > >=20
> > > Hope you are doing well. After  spending a lot of time on this I am
> > > stuck now. Kindly help me resolve this issue or understand it better.
> > >=20
> > > Following your instructions I deleted my config file and copied one f=
rom
> > > the /boot/ directory. After that I enabled the dependencies(CONFIG_OF=
=3Dy
> > > and CONFIG_HAS_IOMEM=3Dy). I was successfully able to enable axis-fif=
o as
> > > a module.
> > >=20
> > > I then ran the following commands:
> > >  - make drivers/staging/axis-fifo/
>=20
> Hey Fabio!
> Sorry for reaching out to you very late. For the past two days I have
> had problems with my Virtual Machine. It is stuck at boot, and this
> happened after it accidentally shut down. I have tried to resolve this
> problem but nothing is working. Currently I have boot into an older
> kernel version from the GRUB menu.
>=20
> I am also sharing the error here:
> Gave up waiting for root device. Common problems:
> -Boot args (cat /proc/cmdline)
>   -Check rootdelay=3D (did the system wait long enough?)
> -Missing modules (cat /proc/modules; ls /dev)
> ALERT! UUID=3D718ed077-947d-4018-80ad-59825678e81d does not exist.
> Dropping to a shell!
> BusyBox v1.27.2 (Ubuntu 1:1.27.2-2ubuntu3.2) built-in shell (ash)
> Enter 'help' for a list of built-in commands.
>=20
> I have Windows10 installed and I have created Ubunutu 22.04.1 VM on VMWare
> with 13GB RAM and 2 processors(4 cores each).
>=20
> (initramfs)_
>=20
> > No, this is not the right command... you are not invoking the linker to=
=20
make
> > the .ko object.
> >=20
> > Use "make M=3Ddrivers/staging/axis-fifo/"
> > or "make M=3Ddrivers/staging/axis-fifo/ W=3D1 -j8" (the latter to enabl=
e level
> > '1' warning and run on your 2 * 4 logical cores).
>=20
> This command gives error saying:
> scripts/Makefile.build:41: /drivers/staging/axis-fifo/Makefile:
> No such file or directory
> make[1]: *** No rule to make target '/drivers/staging/axis-fifo/Makefile'=
=2E=20
> Stop. make: *** [Makefile:2028: /drivers/staging/axis-fifo] Error 2
>=20
> > >  - sudo make modules_install install(this command took hours) :'(
> >=20
> > This is odd, it shouldn't :-/
> >=20
> > As I said in another message, I'll set aside some time to help you chec=
k=20
if
> > you need to fine tune your VM and Hypervisor configuration.
> >=20
> > I'm returning on the same subject we have been talked about because you=
=20
said
> > at least twice that your builds and install are too slow. We'll try to
> > diagnose it in an IRC session on #kernel-outreachy (I'm pretty sure for=
=20
the
> > first days of next week - I'll send an invite).
>=20
> Yes I would love that. Kindly help me with this.
> Thank you!
>=20
> Regards,
> Khadija Kamran
>=20
> > > > When you are done with build, install, and final reboot to test if=
=20
your
> > > > module can "modprobe" or "insmod" (i.e. link with the running custom
> >=20
> > kernel
> >=20
> > > > you built, installed and boot), try to compare the output of the
> > > > following
> > > > commands:
> > > >=20
> > > > # uname -a
> > > > Linux suse 6.2.2-1-default #1 SMP PREEMPT_DYNAMIC Thu Mar  9 06:06:=
13
> > > > UTC
> > > > 2023 (44ca817) x86_64 x86_64 x86_64 GNU/Linux
> > >=20
> > > The above command works
> > >=20
> > > > AND
> > > >=20
> > > > # modinfo <name of the module you are testing here>
> > >=20
> > > On running 'modinfo axis-fifo' I get error saying module axis-fifo not
> > > found.
> >=20
> > Try again after building with "M=3Ddrivers/staging" (as said above). Do=
n't
> > forget to run "make modules_install install" and then reboot into your
> > custom
> > built Kernel, not the distribution's kernel.
> >=20
> > While you are there, run "lsmod" to see all loaded modules. Pick one
> > randomly
> > from the output list and run "modinfo
> > name_of_the_module_you_want_info_about".>=20
> > > > I'm running "modinfo kvm" (but showing only two of many lines):
> > > >=20
> > > > # modinfo kvm
> > > > filename:       /lib/modules/6.2.2-1-default/kernel/arch/x86/kvm/
> >=20
> > kvm.ko.zst
> >=20
> > > > vermagic:       6.2.2-1-default SMP preempt mod_unload modversions
> > > >=20
> > > > Can you see that the kernel in "uname -a" and the filename and=20
vermagic
> >=20
> > have
> >=20
> > > > the same "6.2.2-1-default"? Well, so I'm sure I'm running the right
> > > > Kernel
> > > > and inserted the appropriate "kvm" module.
> > > >=20
> > > > Furthermore, before rebooting your custom kernel, you may also look=
 at
> > > > the
> > > > directory in the Kernel where you compiled your module and search f=
or
> >=20
> > "*.o"
> >=20
> > > > "*mod*" and "*.ko" files. If you have them, you built your module
> >=20
> > properly.
> >=20
> > > There is a "*.o" file and "*.mod" file but there is no "*.ko" file in
> > > the axis-fifo directory.
> > >=20
> > > Kindly help me with this.
> > >=20
> > > Regards,
> > > Khadija
> > >=20
> > > > Thanks,
> > > >=20
> > > > Fabio
> >=20
> > Let me know if this time it works.
> >=20
> > Fabio
> >=20
> > P.S.: Have you had time to read that "Linux Kernel Module Programming"=
=20
guide
> > I sent you the link of? You can find a lot of information about modules
> > there. I'd strongly recommend you to read it.

Khadija,

I think that you are trying to skip some passages. Let me explain better...

Soon after copying from /boot your new .config you should run "make=20
menuconfig" or "make oldconfig" to re-create the necessary dependence and=20
other files which are required to build properly.

I'd suggest "make menuconfig" so that you can check if you enabled correctl=
y=20
the module(s) you are interested to build and other built-in options you ma=
y=20
optionally need.

Then you must rebuild and install. So...

1) "make menuconfig" (don't forget to save before exiting),
2) "make W=3D1 -j8" (because you have 8 logical cores reserved to your VMWa=
re=20
VM, correct?).
3) "make modules_install install".

At this point check that you have a fresh kernel image in /boot, that /boot/
grub/grub.conf contains a new entry with your freshly built custom kernel s=
o=20
that you can boot it from selecting the proper entry in the menu that you'l=
l=20
see after reboot. Also check that you have axis-fifo.ko under /lib/modules/
<the new kernel version>/build/drivers/staging/axis-fifo/.

=46or example in my VM for test I see axis-fifo with...

ls -l /lib/modules/6.3.0-rc2-x86-32-debug+/build/drivers/staging/axis-fifo/
total 564
=2Drw-r--r-- 1 1001 fsgqa    196 Mar 16 20:57 .Module.symvers.cmd
=2Drw-r--r-- 1 1001 fsgqa    275 Mar 17 15:39 .axis-fifo.ko.cmd
=2Drw-r--r-- 1 1001 fsgqa    183 Mar 12 20:29 .axis-fifo.mod.cmd
=2Drw-r--r-- 1 1001 fsgqa  50093 Mar 17 15:39 .axis-fifo.mod.o.cmd
=2Drw-r--r-- 1 1001 fsgqa  61110 Mar 17 15:37 .axis-fifo.o.cmd
=2Drw-r--r-- 1 1001 fsgqa    147 Mar 17 15:37 .modules.order.cmd
=2Drw-r--r-- 1 1001 fsgqa      0 Mar 16 20:57 Module.symvers
=2Drw-r--r-- 1 1001 fsgqa 255748 Mar 17 15:39 axis-fifo.ko
=2Drw-r--r-- 1 1001 fsgqa     38 Mar 12 20:29 axis-fifo.mod
=2Drw-r--r-- 1 1001 fsgqa   2354 Mar 17 15:38 axis-fifo.mod.c
=2Drw-r--r-- 1 1001 fsgqa  44604 Mar 17 15:39 axis-fifo.mod.o
=2Drw-r--r-- 1 1001 fsgqa 128156 Mar 17 15:37 axis-fifo.o
=2Drw-r--r-- 1 1001 fsgqa     38 Mar 17 15:37 modules.order

(as you can see, the last time I built and installed the kernel and the axi=
s-
fifo driver's module was March 17, 15:39).

Please notice that my kernel has that "-x86-32-debug+" suffix after the ker=
nel=20
version but this depends on a special option I need to set to differentiate=
=20
"debug" kernels from "production" kernels. You may have something else that=
=20
your distribution appends.

If you can't find the module run again "ls -l" one level up, like in /lib/
modules/6.3.0-rc2-x86-32-debug+/build/drivers/staging/ to see if at least y=
ou=20
have any of the drivers/staging/ modules. Go one more layer up if you don't=
=20
find them.

If everything I cited above is where it is supposed to be and grub.conf is=
=20
properly configured with the new entry, reboot and enjoy your module (try=20
modprobe, modinfo, lsmod, and the likes).

=46abio=20

=46abio