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. Alexey Gladkov (7): mfd: stmpe-spi: Correct the name used in MODULE_DEVICE_TABLE scsi: Define MODULE_DEVICE_TABLE only if necessary modules: Add macros to specify modinfo prefix modpost: Make mod_device_table aliases more unique modpost: Create modalias for builtin modules kbuild: Move modules.builtin.modinfo to another makefile kbuild: Create modules.builtin.modinfo for modpost results drivers/mfd/stmpe-spi.c | 2 +- drivers/scsi/BusLogic.c | 2 +- include/linux/module.h | 21 +++++++++++----- include/linux/moduleparam.h | 7 ++++-- scripts/Makefile.vmlinux | 50 +++++++++++++++++++++++++++++++++++++ scripts/Makefile.vmlinux_o | 26 +------------------ scripts/mod/file2alias.c | 31 +++++++++++++++++++---- scripts/mod/modpost.c | 21 +++++++++++++--- scripts/mod/modpost.h | 7 +++++- 9 files changed, 123 insertions(+), 44 deletions(-) -- 2.49.0
