Hello Qiang,
On 2024-06-26 08:49, Dragan Simic wrote:
> On 2024-06-26 03:11, Qiang Yu wrote:
>> On Wed, Jun 26, 2024 at 2:15 AM Dragan Simic <dsimic@xxxxxxxxxxx>
>> wrote:
>>> Just checking, any further thoughts about this patch?
>>>
>> I'm OK with this as a temp workaround because it's simple and do no
>> harm
>> even it's not perfect. If no other better suggestion for short term,
>> I'll submit
>> this at weekend.
>
> Thanks. Just as you described it, it's far from perfect, but it's
> still
> fine until there's a better solution, such as harddeps. I'll continue
> my
> research about the possibility for adding harddeps, which would
> hopefully
> replace quite a few instances of the softdep (ab)use.
Another option has become available for expressing additional module
dependencies, weakdeps. [1][2] Long story short, weakdeps are similar
to softdeps, in the sense of telling the initial ramdisk utilities to
include additional kernel modules, but weakdeps result in no module
loading being performed by userspace.
Maybe "weak" isn't the best possible word choice (arguably, "soft"
also
wasn't the best word choice), but weakdeps should be a better choice
for
use with Lima and governor_simpleondemand, because weakdeps provide
the
required information to the utilities used to generate initial
ramdisk,
while the actual module loading is left to the kernel.
The recent addition of weakdeps renders the previously mentioned
harddeps
obsolete, because weakdeps actually do what we need. Obviously,
"weak"
doesn't go along very well with the actual nature of the dependency
between
Lima and governor_simpleondemand, but it's pretty much just the
somewhat
unfortunate word choice.
The support for weakdeps has been already added to the kmod [3][4] and
Dracut [5] userspace utilities. I'll hopefully add support for
weakdeps
to mkinitcpio [6] rather soon.
Maybe we could actually add MODULE_HARDDEP() as some kind of syntactic
sugar, which would currently be an alias for MODULE_WEAKDEP(), so the
actual hard module dependencies could be expressed properly, and
possibly
handled differently in the future, with no need to go back and track
all
such instances of hard module dependencies.
With all this in mind, here's what I'm going to do:
1) Submit a patch that adds MODULE_HARDDEP() as syntactic sugar
2) Implement support for weakdeps in Arch Linux's mkinitcpio [6]
3) Depending on what kind of feedback the MODULE_HARDDEP() patch
receives,
I'll submit follow-up patches for Lima and Panfrost, which will
swap
uses of MODULE_SOFTDEP() with MODULE_HARDDEP() or MODULE_WEAKDEP()
Looking forward to your thoughts.
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/module.h?id=61842868de13aa7fd7391c626e889f4d6f1450bf
[2]
https://lore.kernel.org/linux-kernel/20240724102349.430078-1-jtornosm@xxxxxxxxxx/T/#u
[3]
https://github.com/kmod-project/kmod/commit/05828b4a6e9327a63ef94df544a042b5e9ce4fe7
[4]
https://github.com/kmod-project/kmod/commit/d06712b51404061eef92cb275b8303814fca86ec
[5]
https://github.com/dracut-ng/dracut-ng/commit/8517a6be5e20f4a6d87e55fce35ee3e29e2a1150
[6] https://gitlab.archlinux.org/archlinux/mkinitcpio/mkinitcpio
