linux-kernel - Re: [PATCH v4 0/7] Add generated modalias to modules.builtin.modinfo

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Message-ID: <aHUI8KqD0_dtTY3D@example.org>
Date: Mon, 14 Jul 2025 15:41:04 +0200
From: Alexey Gladkov <legion@...nel.org>
To: Masahiro Yamada <masahiroy@...nel.org>,
	Petr Pavlu <petr.pavlu@...e.com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Daniel Gomez <da.gomez@...sung.com>,
	Nathan Chancellor <nathan@...nel.org>,
	Nicolas Schier <nicolas.schier@...ux.dev>
Cc: linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
	linux-kbuild@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH v4 0/7] Add generated modalias to modules.builtin.modinfo

On Sat, Jun 21, 2025 at 03:57:12PM +0200, Alexey Gladkov wrote:
> The modules.builtin.modinfo file is used by userspace (kmod to be specific) to
> get information about builtin modules. Among other information about the module,
> information about module aliases is stored. This is very important to determine
> that a particular modalias will be handled by a module that is inside the
> kernel.
> 
> There are several mechanisms for creating modalias for modules:
> 
> The first is to explicitly specify the MODULE_ALIAS of the macro. In this case,
> the aliases go into the '.modinfo' section of the module if it is compiled
> separately or into vmlinux.o if it is builtin into the kernel.
> 
> The second is the use of MODULE_DEVICE_TABLE followed by the use of the
> modpost utility. In this case, vmlinux.o no longer has this information and
> does not get it into modules.builtin.modinfo.
> 
> For example:
> 
> $ modinfo pci:v00008086d0000A36Dsv00001043sd00008694bc0Csc03i30
> modinfo: ERROR: Module pci:v00008086d0000A36Dsv00001043sd00008694bc0Csc03i30 not found.
> 
> $ modinfo xhci_pci
> name:           xhci_pci
> filename:       (builtin)
> license:        GPL
> file:           drivers/usb/host/xhci-pci
> description:    xHCI PCI Host Controller Driver
> 
> The builtin module is missing alias "pci:v*d*sv*sd*bc0Csc03i30*" which will be
> generated by modpost if the module is built separately.
> 
> To fix this it is necessary to add the generated by modpost modalias to
> modules.builtin.modinfo.
> 
> Fortunately modpost already generates .vmlinux.export.c for exported symbols. It
> is possible to use this file to create a '.modinfo' section for builtin modules.
> The modules.builtin.modinfo file becomes a composite file. One part is extracted
> from vmlinux.o, the other part from .vmlinux.export.o.

Masahiro Yamada, does this version of the patchset look better to you ?

> Notes:
> - v4:
>   * Rework the patchset based on top of Masahiro Yamada's patches.
>   * Add removal of unnecessary __mod_device_table__* symbols to avoid symbol
>     table growth in vmlinux.
>   * rust code takes into account changes in __mod_device_table__*.
>   * v3: https://lore.kernel.org/all/cover.1748335606.git.legion@kernel.org/
> 
> - v3:
>   * Add `Reviewed-by` tag to patches from Petr Pavlu.
>   * Rebase to v6.15.
>   * v2: https://lore.kernel.org/all/20250509164237.2886508-1-legion@kernel.org/
> 
> - v2:
>   * Drop patch for mfd because it was already applied and is in linux-next.
>   * The generation of aliases for builtin modules has been redone as
>     suggested by Masahiro Yamada.
>   * Rebase to v6.15-rc5-136-g9c69f8884904
>   * v1: https://lore.kernel.org/all/cover.1745591072.git.legion@kernel.org/
> 
> 
> Alexey Gladkov (3):
>   scsi: Always define blogic_pci_tbl structure
>   modpost: Add modname to mod_device_table alias
>   modpost: Create modalias for builtin modules
> 
> Masahiro Yamada (4):
>   module: remove meaningless 'name' parameter from __MODULE_INFO()
>   kbuild: always create intermediate vmlinux.unstripped
>   kbuild: keep .modinfo section in vmlinux.unstripped
>   kbuild: extract modules.builtin.modinfo from vmlinux.unstripped
> 
>  drivers/scsi/BusLogic.c           |  2 -
>  include/asm-generic/vmlinux.lds.h |  2 +-
>  include/crypto/algapi.h           |  4 +-
>  include/linux/module.h            | 21 ++++-----
>  include/linux/moduleparam.h       |  9 ++--
>  include/net/tcp.h                 |  4 +-
>  rust/kernel/device_id.rs          |  8 ++--
>  scripts/Makefile.vmlinux          | 74 +++++++++++++++++++++----------
>  scripts/Makefile.vmlinux_o        | 26 +----------
>  scripts/mksysmap                  |  6 +++
>  scripts/mod/file2alias.c          | 34 ++++++++++++--
>  scripts/mod/modpost.c             | 17 ++++++-
>  scripts/mod/modpost.h             |  2 +
>  13 files changed, 131 insertions(+), 78 deletions(-)
> 
> -- 
> 2.49.0
> 

-- 
Rgrds, legion