Messages in this thread | | | Subject | Re: Differences between builtins and modules | From | Randy Dunlap <> | Date | Fri, 6 Apr 2018 18:00:09 -0700 |
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On 02/24/2015 05:02 PM, Lucas De Marchi wrote: > On Mon, Feb 23, 2015 at 12:51 PM, Michal Marek <mmarek@suse.cz> wrote: >> On 2015-02-23 15:30, Lucas De Marchi wrote: >>> This could be particularly bad if in a kernel version an option was >>> tristate and in a new version it changed to boolean. I'm not sure if >>> this is common to happen in kernel. Any code that did "modprobe >>> <module>" would start to fail. >> >> I think it's quite uncommon (*) and also the use case for loading >> builtin modules is not that common. I can think of: >> 1) building the initramfs, to determine which *.ko files need to be >> copied to it. Since such tools are often updated for other reasons, >> it's not a big deal. >> 2) Hardcoded module names in things like softdep -- hopefully not that >> common either, plus the kernel-provided soft dependencies can be >> fixed together with the change. >> >> Until not so long ago, the kernel would return EINVAL if passed a >> non-existent (renamed, removed) module option to init_module, yet there >> were no attempts at preserving the module options for compatibility reasons. >> >> (*) I now did a quick search: >> $ git log -p origin/master --no-merges -- '*/Kconfig*' | grep -C3 '^- >> *tristate' | grep '^+ *bool' >> + bool "Intel P state control" >> + bool "Intel microcode patch loading support" >> + bool "AMD microcode patch loading support" >> + bool "STI text console" >> + bool "Enable DDC2 Support" >> + bool "Enable Console Acceleration" >> >> That's only 6 cases in the whole git history. Maybe there are a few more >> hidden outside the three-line context as part of larger edits, but I'm >> sure more modules have been *removed* entirely from the kernel over this >> period. > > thanks for looking in detail into this. > >> >> >>> My questions are: >>> 1) should we put *all* the "modules" in the builtin index? >> >> You mean all *.o files that do not end up in some *.ko? That won't work, >> because unlike module names, the names of object files are not global. > > I was actually meaning anything that can have a directory under > /sys/module/. I figure we can't easily know this. > >> Plus, there was IIRC an idea to teach lsmod to print builtin modules -- >> listing all *.o would make it rather useless. > > This was one of my ideas... to traverse /sys/module and give more > information than we actually output right now, including builtin > modules. However, given the fact that builtin modules only have an > entry in /sys/module if they have params and now that I'm aware of the > race between the creation of the directory and the initstate file, I'm > giving up on this idea for now. > >>> 2) should we actually check /sys/module/<modulename> to report a >>> module as builtin or just stop doing that and rely solely in the >>> index? Initially I'd like to do the opposite, but given the race in >>> deciding this I'm favoring the index. >> >> If the race between the creation of /sys/module/<modulename> and >> /sys/module/<modulename>/initstate is inevitable, then I'm afraid we >> have to rely on the index. > > So my current plan is to rely solely on modules.builtin to output to > modprobe that a module is builtin. So things like "modprobe vt" will > start to fail saying there's no vt module. Any objections here? >
Hi, [sorry to resurrect such as old thread]
Would someone please answer/reply to this (related) kernel bugzilla entry: https://bugzilla.kernel.org/show_bug.cgi?id=118661
or I could just close it?
thanks, -- ~Randy
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