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It has been seen that for some network mac drivers (i.e. lan78xx) the related module for the phy is loaded dynamically depending on the current hardware. In this case, the associated phy is read using mdio bus and then the associated phy module is loaded during runtime (kernel function phy_request_driver_module). However, no software dependency is defined, so the user tools will no be able to get this dependency. For example, if dracut is used and the hardware is present, lan78xx will be included but no phy module will be added, and in the next restart the device will not work from boot because no related phy will be found during initramfs stage. In order to solve this, we could define a normal 'pre' software dependency in lan78xx module with all the possible phy modules (there may be some), but proceeding in that way, all the possible phy modules would be loaded while only one is necessary. The idea is to create a new type of dependency, that we are going to call 'weak' to be used only by the user tools that need to detect this situation. In that way, for example, dracut could check the 'weak' dependency of the modules involved in order to install these dependencies in initramfs too. That is, for the commented lan78xx module, defining the 'weak' dependency with the possible phy modules list, only the necessary phy would be loaded on demand keeping the same behavior, but all the possible phy modules would be available from initramfs. A new function 'kmod_module_get_weakdeps' in libkmod will be added for this to avoid breaking the API and maintain backward compatibility. This general procedure could be useful for other similar cases (not only for dynamic phy loading). Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com> Link: https://lore.kernel.org/r/20240327141116.97587-1-jtornosm@redhat.com |
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| .. | ||
| docs | ||
| .gitignore | ||
| COPYING | ||
| libkmod-builtin.c | ||
| libkmod-config.c | ||
| libkmod-elf.c | ||
| libkmod-file.c | ||
| libkmod-index.c | ||
| libkmod-index.h | ||
| libkmod-internal.h | ||
| libkmod-list.c | ||
| libkmod-module.c | ||
| libkmod-signature.c | ||
| libkmod.c | ||
| libkmod.h | ||
| libkmod.pc.in | ||
| libkmod.sym | ||
| Makefile | ||
| README | ||
libkmod - linux kernel module handling library
ABSTRACT
========
libkmod was created to allow programs to easily insert, remove and
list modules, also checking its properties, dependencies and aliases.
there is no shared/global context information and it can be used by
multiple sites on a single program, also being able to be used from
threads, although it's not thread safe (you must lock explicitly).
OVERVIEW
========
Every user should create and manage it's own library context with:
struct kmod_ctx *ctx = kmod_new(kernel_dirname);
kmod_unref(ctx);
Modules can be created by various means:
struct kmod_module *mod;
int err;
err = kmod_module_new_from_path(ctx, path, &mod);
if (err < 0) {
/* code */
} else {
/* code */
kmod_module_unref(mod);
}
err = kmod_module_new_from_name(ctx, name, &mod);
if (err < 0) {
/* code */
} else {
/* code */
kmod_module_unref(mod);
}
Or could be resolved from a known alias to a list of alternatives:
struct kmod_list *list, *itr;
int err;
err = kmod_module_new_from_lookup(ctx, alias, &list);
if (err < 0) {
/* code */
} else {
kmod_list_foreach(itr, list) {
struct kmod_module *mod = kmod_module_get_module(itr);
/* code */
}
}