[gentoo-user] preparing for make menuconfig

[gentoo-user] preparing for make menuconfig

[Jude DaShiell]

I installed lspci and ran the command.
On the first line lspci says
Unable to load libkmod resources.
Lots of information provided after that though.
Are libkmod resources used by sound cards?  I have sound working
on the system to be installed since I'm using espeak to do the
installation.  Does any way to clear this error exist or it may
be a warning let's see, lspci exited with a 0 errorlevel so that must have
been a warning.Is it likely be unnecessary to clear this warning?


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Re: [gentoo-user] preparing for make menuconfig

[Ashley Dixon]

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On Thu, Oct 08, 2020 at 01:54:22AM -0400, Jude DaShiell wrote:
> Are libkmod resources used by sound cards? 

libkmod, as described at [1], is a "set of tools to  handle  common  tasks  with
Linux kernel modules  like  insert,  remove,  list,  check  properties,  resolve
dependencies and aliases".  This is just a total guess, but I can  suppose  that
lspci uses it to convey which kernel modules are being used by each PCI  device.

Can you post the full command and output?  Are you getting  a  particular  error
message/number, such as the one at [2]?  Please, whenever you encounter an error
like this, be as *verbose as (reasonably) possible* when asking for help. If you
don't provide enough information for an effective triage, many watchers of  this
list will just ignore your query.

> I have sound working on the system to be installed since I'm using espeak to
> do the installation.  Does any way to clear this error exist or it may be a
> warning let's see, lspci exited with a 0 errorlevel so that must have been a
> warning.Is it likely be unnecessary to clear this warning?

It's probably nothing to do with your sound card.  It just sounds like an  issue
with lspci. Please provide the requested information.

(P.S.  The subject has nothing to do with the content.  I suggest changing it to
something more appropriate, along the lines of  "lspci  cannot  load  libkmod"?)

[1] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/about/
[2] https://github.com/NixOS/nixpkgs/issues/20683

-- 

Ashley Dixon
suugaku.co.uk

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Re: [gentoo-user] preparing for make menuconfig

[Ashley Dixon]

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On Thu, Oct 08, 2020 at 07:30:45AM +0100, Ashley Dixon wrote:
> This is just a total guess, but I can suppose that lspci uses it to convey
> which kernel modules are being used by each PCI device.

Clarification: kmod is used specifically with the `-k` switch of lspci:

        $ ash-euses -o pciutils:kmod
        sys-apps/pciutils:kmod - Enable sys-apps/kmod support for the -k switch
        in lspci command

This causes the LIBKMOD variable to be passed to the Makefile [1, 2]:

        pemake() {
            emake \
                [...]
                LIBKMOD=$(multilib_native_usex kmod) \
                [...]
                "$@"
        }

Anyway, with regards to your problem: if you're just installing your system now,
then you're probably getting this error  because  `/lib/modules`  doesn't  exist
inside your chroot.  This path is hardcoded into pciutils  [3];  this  has  been
modified by some vendors of the package, but not Gentoo [4].  You needn't  worry
unless you're still getting this error  outside  of  your  chroot,  once  you've
completed the installation. Just focus on building a kernel for now.

[1] https://gitweb.gentoo.org/repo/gentoo.git/tree/sys-apps/pciutils/pciutils-3.7.0.ebuild#n81
[2] https://devmanual.gentoo.org/eclass-reference/multilib-build.eclass/#lbAE
[3] https://git.kernel.org/pub/scm/utils/pciutils/pciutils.git/tree/ls-kernel.c#n134
[4] https://github.com/NixOS/nixpkgs/commit/286c836b3f1421553c103758537929e596256e65#diff-0a685886728285db8aa0594d87cb29b4

-- 

Ashley Dixon
suugaku.co.uk

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Re: [gentoo-user] preparing for make menuconfig

[John Covici]

On Thu, 08 Oct 2020 02:51:49 -0400,
Ashley Dixon wrote:
> 
> [1  <text/plain; us-ascii (quoted-printable)>]
> On Thu, Oct 08, 2020 at 07:30:45AM +0100, Ashley Dixon wrote:
> > This is just a total guess, but I can suppose that lspci uses it to convey
> > which kernel modules are being used by each PCI device.
> 
> Clarification: kmod is used specifically with the `-k` switch of lspci:
> 
>         $ ash-euses -o pciutils:kmod
>         sys-apps/pciutils:kmod - Enable sys-apps/kmod support for the -k switch
>         in lspci command
> 
> This causes the LIBKMOD variable to be passed to the Makefile [1, 2]:
> 
>         pemake() {
>             emake \
>                 [...]
>                 LIBKMOD=$(multilib_native_usex kmod) \
>                 [...]
>                 "$@"
>         }
> 
> Anyway, with regards to your problem: if you're just installing your system now,
> then you're probably getting this error  because  `/lib/modules`  doesn't  exist
> inside your chroot.  This path is hardcoded into pciutils  [3];  this  has  been
> modified by some vendors of the package, but not Gentoo [4].  You needn't  worry
> unless you're still getting this error  outside  of  your  chroot,  once  you've
> completed the installation. Just focus on building a kernel for now.
> 
> [1] https://gitweb.gentoo.org/repo/gentoo.git/tree/sys-apps/pciutils/pciutils-3.7.0.ebuild#n81
> [2] https://devmanual.gentoo.org/eclass-reference/multilib-build.eclass/#lbAE
> [3] https://git.kernel.org/pub/scm/utils/pciutils/pciutils.git/tree/ls-kernel.c#n134
> [4] https://github.com/NixOS/nixpkgs/commit/286c836b3f1421553c103758537929e596256e65#diff-0a685886728285db8aa0594d87cb29b4

I always get this error, but the flag indicating which driver is being
used still works, so I have not paid too much attention to this one.
I do have a running system with /lib/modules and the error still
occurrs.

-- 
Your life is like a penny.  You're going to lose it.  The question is:
How do
you spend it?

         John Covici wb2una
         covici@ccs.covici.com

Re: [gentoo-user] preparing for make menuconfig

[Ashley Dixon]

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On Thu, Oct 08, 2020 at 07:04:46AM -0400, John Covici wrote:
> I always get this error, but the flag indicating which driver is being
> used still works, so I have not paid too much attention to this one.
> I do have a running system with /lib/modules and the error still
> occurrs.

What is the exact error?  Is it accompanied by an error code?  libkmod looks for
the following files, typically  located  in  `/lib/modules/$(uname  -r)/`,  when
client applications request a context [1]; most of these can be  generated  with
depmod(8):

 - modules.dep
 - modules.alias
 - modules.symbols
 - modules.builtin.alias
 - modules.builtin

        struct _index_files {
                const char *fn;
                const char *prefix;
        }

The most interesting for kernel modules is `modules.alias`, which  is  the  more
modern representation of `modules.{pci,usb}map` [2].  Are all these files intact
on your system? What happens when you run `lsmod`?

[1] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/libkmod/libkmod.c#n53
[2] https://stackoverflow.com/a/25644147/

-- 

Ashley Dixon
suugaku.co.uk

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Re: [gentoo-user] preparing for make menuconfig

[John Covici]

On Thu, 08 Oct 2020 11:07:44 -0400,
Ashley Dixon wrote:
> 
> [1  <text/plain; us-ascii (quoted-printable)>]
> On Thu, Oct 08, 2020 at 07:04:46AM -0400, John Covici wrote:
> > I always get this error, but the flag indicating which driver is being
> > used still works, so I have not paid too much attention to this one.
> > I do have a running system with /lib/modules and the error still
> > occurrs.
> 
> What is the exact error?  Is it accompanied by an error code?  libkmod looks for
> the following files, typically  located  in  `/lib/modules/$(uname  -r)/`,  when
> client applications request a context [1]; most of these can be  generated  with
> depmod(8):
> 
>  - modules.dep
>  - modules.alias
>  - modules.symbols
>  - modules.builtin.alias
>  - modules.builtin
> 
>         struct _index_files {
>                 const char *fn;
>                 const char *prefix;
>         }
> 
> The most interesting for kernel modules is `modules.alias`, which  is  the  more
> modern representation of `modules.{pci,usb}map` [2].  Are all these files intact
> on your system? What happens when you run `lsmod`?
> 
> [1] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/libkmod/libkmod.c#n53
> [2] https://stackoverflow.com/a/25644147/

I have the following in my running kernel:

modules.alias              modules.builtin
modules.builtin.bin        modules.dep.bin            modules.order
modules.symbols
modules.alias.bin          modules.builtin.alias.bin  modules.dep
modules.devname            modules.softdep
modules.symbols.bin

and the error message is

lspci: Unable to load libkmod resources: error -12


-- 
Your life is like a penny.  You're going to lose it.  The question is:
How do
you spend it?

         John Covici wb2una
         covici@ccs.covici.com

Re: [gentoo-user] preparing for make menuconfig

[Ashley Dixon]

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On Thu, Oct 08, 2020 at 01:55:04PM -0400, John Covici wrote:
> modules.alias              modules.builtin
> modules.builtin.bin        modules.dep.bin            modules.order
> modules.symbols
> modules.alias.bin          modules.builtin.alias.bin  modules.dep
> modules.devname            modules.softdep
> modules.symbols.bin

That's fine.

> and the error message is
> 
> lspci: Unable to load libkmod resources: error -12

That error message is printed by lspci [1], although it is  the  result  of  the
libkmod `kmod_load_resources` function returning less than zero [2].  With a -12
error, this suggests a failing with the `index_mm_open` function [3]. It's quite
a beast of a function; the failure could be due to a multitude of reasons.

Considering the nature of the error (memory allocation  failure),  I  reckon  it
must be either the following call to mmap(2), or the preceding call to  open(2):
(paraphrasing for formatting):


	if ((fd = open(filename, O_RDONLY|O_CLOEXEC)) < 0) {
		DBG(ctx, "open(%s, O_RDONLY|O_CLOEXEC): %m\n", filename);
		err = -errno;
		goto fail_open;
	}

        /* [...] */

	if ( ( idx->mm = mmap ( NULL, st.st_size, PROT_READ,
                                        MAP_PRIVATE, fd, 0 ) ) == MAP_FAILED) {
		ERR(ctx, "mmap (NULL, %"PRIu64", PROT_READ, %d, " \
                                "MAP_PRIVATE, 0 ): %m\n", st.st_size, fd);
		err = -errno;
		goto fail_nommap;
	}

I might you need to debug this on your machine, as I can't reproduce it  myself.
You'll need to clone, recompile,  and  relink  libkmod  and  pciutils  with  the
maximum debugging settings, to keep all symbols in  the  executable.   I  assume
you're using GCC, although I suspect the same should work with Clang.

git clone both repos: [4] and [5].

libkmod:
        - Save the old symlink, by renaming /lib64/libkmod.<version> to
          something temporary, like libkmod.old.
        - Execute ./autogen.sh to create a configure script.
        - Run the configure script to enable maximum debugging:
                ./configure CFLAGS='-ggdb3' --prefix=/usr --sysconfdir=/etc \
                --libdir=/usr/lib64 --with-rootprefix= --with-rootlibdir=/lib64
        - Compile and install the shared objects (you need to be root):
                make && make install
        - Ensure the `make install` has recreated the major version symlink in
          /lib64 to the new shared object file.

pciutils:
        - Compile; there is no need to install:
                make CFLAGS="-ggdb3"

Now you have an lspci executable which is linked with the new libkmod, just need
to attach a debugger, such as gdb, and break on the troublesome function:

        $ gdb ./lspci
        Reading symbols from ./lspci...
        (gdb) b index_mm_open
        Function "index_mm_open" not defined.
        Make breakpoint pending on future shared library load? (y or [n]) y
        Breakpoint 1 (index_mm_open) pending.
        (gdb) run -k

... after a while, you'll encounter the first invocation of the troublemaker:

        Breakpoint 1, index_mm_open (ctx=0x555555583340, filename=0x7fffffffc920
            "/lib/modules/5.4.60-gentoo/modules.dep.bin", stamp=0x5555555833a0,
            pidx=0x555555583378) at libkmod/libkmod-index.c:744

Before going any further, I want to confirm that  `filename`  does  point  to  a
correct file?  I doubt the open(2) call would fail with ENOMEM if the  file  was
invalid, although you never know.  Assuming `filename` is valid,  we  can  start
stepping through the function to determine which inner function is failing.   My
bets are on mmap.

Hope to hear from you soon.

[1] https://git.kernel.org/pub/scm/utils/pciutils/pciutils.git/tree/ls-kernel.c#n42
[2] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/libkmod/libkmod.c#n842
[3] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/libkmod/libkmod-index.c#n742
[4] git://git.kernel.org/pub/scm/utils/pciutils/pciutils.git
[5] git://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git

-- 

Ashley Dixon
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Re: [gentoo-user] preparing for make menuconfig

[John Covici]

On Thu, 08 Oct 2020 16:26:19 -0400,
Ashley Dixon wrote:
> 
> [1  <text/plain; us-ascii (quoted-printable)>]
> On Thu, Oct 08, 2020 at 01:55:04PM -0400, John Covici wrote:
> > modules.alias              modules.builtin
> > modules.builtin.bin        modules.dep.bin            modules.order
> > modules.symbols
> > modules.alias.bin          modules.builtin.alias.bin  modules.dep
> > modules.devname            modules.softdep
> > modules.symbols.bin
> 
> That's fine.
> 
> > and the error message is
> > 
> > lspci: Unable to load libkmod resources: error -12
> 
> That error message is printed by lspci [1], although it is  the  result  of  the
> libkmod `kmod_load_resources` function returning less than zero [2].  With a -12
> error, this suggests a failing with the `index_mm_open` function [3]. It's quite
> a beast of a function; the failure could be due to a multitude of reasons.
> 
> Considering the nature of the error (memory allocation  failure),  I  reckon  it
> must be either the following call to mmap(2), or the preceding call to  open(2):
> (paraphrasing for formatting):
> 
> 
> 	if ((fd = open(filename, O_RDONLY|O_CLOEXEC)) < 0) {
> 		DBG(ctx, "open(%s, O_RDONLY|O_CLOEXEC): %m\n", filename);
> 		err = -errno;
> 		goto fail_open;
> 	}
> 
>         /* [...] */
> 
> 	if ( ( idx->mm = mmap ( NULL, st.st_size, PROT_READ,
>                                         MAP_PRIVATE, fd, 0 ) ) == MAP_FAILED) {
> 		ERR(ctx, "mmap (NULL, %"PRIu64", PROT_READ, %d, " \
>                                 "MAP_PRIVATE, 0 ): %m\n", st.st_size, fd);
> 		err = -errno;
> 		goto fail_nommap;
> 	}
> 
> I might you need to debug this on your machine, as I can't reproduce it  myself.
> You'll need to clone, recompile,  and  relink  libkmod  and  pciutils  with  the
> maximum debugging settings, to keep all symbols in  the  executable.   I  assume
> you're using GCC, although I suspect the same should work with Clang.
> 
> git clone both repos: [4] and [5].
> 
> libkmod:
>         - Save the old symlink, by renaming /lib64/libkmod.<version> to
>           something temporary, like libkmod.old.
>         - Execute ./autogen.sh to create a configure script.
>         - Run the configure script to enable maximum debugging:
>                 ./configure CFLAGS='-ggdb3' --prefix=/usr --sysconfdir=/etc \
>                 --libdir=/usr/lib64 --with-rootprefix= --with-rootlibdir=/lib64
>         - Compile and install the shared objects (you need to be root):
>                 make && make install
>         - Ensure the `make install` has recreated the major version symlink in
>           /lib64 to the new shared object file.
> 
> pciutils:
>         - Compile; there is no need to install:
>                 make CFLAGS="-ggdb3"
> 
> Now you have an lspci executable which is linked with the new libkmod, just need
> to attach a debugger, such as gdb, and break on the troublesome function:
> 
>         $ gdb ./lspci
>         Reading symbols from ./lspci...
>         (gdb) b index_mm_open
>         Function "index_mm_open" not defined.
>         Make breakpoint pending on future shared library load? (y or [n]) y
>         Breakpoint 1 (index_mm_open) pending.
>         (gdb) run -k
> 
> ... after a while, you'll encounter the first invocation of the troublemaker:
> 
>         Breakpoint 1, index_mm_open (ctx=0x555555583340, filename=0x7fffffffc920
>             "/lib/modules/5.4.60-gentoo/modules.dep.bin", stamp=0x5555555833a0,
>             pidx=0x555555583378) at libkmod/libkmod-index.c:744
> 
> Before going any further, I want to confirm that  `filename`  does  point  to  a
> correct file?  I doubt the open(2) call would fail with ENOMEM if the  file  was
> invalid, although you never know.  Assuming `filename` is valid,  we  can  start
> stepping through the function to determine which inner function is failing.   My
> bets are on mmap.
> 
> Hope to hear from you soon.
> 
> [1] https://git.kernel.org/pub/scm/utils/pciutils/pciutils.git/tree/ls-kernel.c#n42
> [2] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/libkmod/libkmod.c#n842
> [3] https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/libkmod/libkmod-index.c#n742
> [4] git://git.kernel.org/pub/scm/utils/pciutils/pciutils.git
> [5] git://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git
> 


Since I compile most packages with split-debug and my default flags
contain -gdb, could I use  the existing packages?

-- 
Your life is like a penny.  You're going to lose it.  The question is:
How do
you spend it?

         John Covici wb2una
         covici@ccs.covici.com

Re: [gentoo-user] preparing for make menuconfig

[Ashley Dixon]

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On Thu, Oct 08, 2020 at 06:50:16PM -0400, John Covici wrote:
> Since I compile most packages with split-debug and my default flags
> contain -gdb, could I use  the existing packages?

LOL, I feel like I might have overcomplicated that. ;-)

I'm not sure if it will keep as many symbols as `-ggdb3`, but you probably don't
need that many anyway.  Remember to enable the `splitdebug` and `installsources`
FEATURES on both packages. Following the Gentoo guide [1]:

        /etc/portage/ $ cat env/debugsyms env/installsources
        CFLAGS="${CFLAGS} -ggdb"
        CXXFLAGS="${CXXFLAGS} -ggdb"
        FEATURES="${FEATURES} splitdebug compressdebug nostrip"
        FEATURES="${FEATURES} installsources"

        /etc/portage/ $ cat package.env/sys-apps/kpci
        sys-apps/kmod debugsyms installsources
        sys-apps/pciutils debugsyms installsources

        $ emerge -atv1 kmod pciutils

I'm not sure what you mean by "my default flags contain -gdb".  Are  these  your
CFLAGS (in which case I think you mean `-ggdb`),  or  is  it  some  USE-flag  or
FEATURE of which I'm unaware?

Anyway, then you should be able to break at the same function as  before,  using
the globally installed version of `lspci`:

        $ gdb lspci
        Reading symbols from lspci...
        (gdb) b index_mm_open
        Function "index_mm_open" not defined.
        Make breakpoint pending on future shared library load? (y or [n]) y
        Breakpoint 1 (index_mm_open) pending.
        (gdb) run -k
        Starting program: /usr/sbin/lspci -k

        [...]

        Breakpoint 1, index_mm_open (ctx=ctx@entry=0x555555570b30,
            filename=filename@entry=0x7fffffffc9a0
            "/lib/modules/5.4.60-gentoo/modules.dep.bin",
            stamp=stamp@entry=0x555555570b90) at
            /usr/src/debug/sys-apps/kmod-27-r2/kmod-27/libkmod/libkmod-index.c
            :744

Cheers for pointing this out. I'm still not completely accustomed to using Linux
with a _good_ package manager. ;-)

[1] https://wiki.gentoo.org/wiki/Debugging#Install_debugging_information

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