On 2022-06-04 07:18, Bjoern A. Zeeb wrote:
On Fri, 3 Jun 2022, Pau Amma wrote:
Currently, 3 section 4 manual pages say to use kld_list in rc.conf for
loading: acpi_video(4), iwlwifi(4), and rtw88(4). Contrasting this
with 367 following share/examples/mdoc/example.4's lead and
instructing to use loader(8)-time loading, the current approach
appears to be: loader(8)-time unless it needs rc(8)-time loading
(explicitly discouraged for iwlwifi(4) and rtw88(4), which say to rely
on devmatch(8) if at all possible). However, this may not be the best
idea, considering:
rc.conf(5):
kld_list (str) A list of kernel modules to load right after the
local
disks are mounted. Loading modules at this point in
the boot
process is much faster than doing it via
/boot/loader.conf
for those modules not necessary for mounting local
disk.
devmatch(8) itself, as already mentioned, which aims to make explicit
loading (either way) unnecessary in most cases;
several Freenode^WLibera #freebsd discussions, in at least one of
which kevans stated that rc(8) loading was much safer, especially for
large modules or drivers.
What was the cause for that assumption? I assume that both just run
kldload.
Safer than loader, I mean, not safer than devmatch.
So I think the default suggestion should be changed from loader.conf
to rc.conf, or maybe to; devmatch preferred, or rc.conf if not an
option.
Thoughts?
The problem is more tricky. Not all drivers do provide data for
devmatch to work yet.
Also some drivers do want to be loaded from loader and not later as
they might be essential for booting to multi-user.
I know *eyes the ZFS-on-root laptop he's writing this on* but how many
are there in that category?
I am generally tempted to remove the boiler plate from almost all man
pages (once the driver supports devmatch) and have a separate man page
to point at for how (many ways) to load a driver, possibly along (if it
needs special requirements) a suggested hint of which way to use.
That would work as well, but as long as we're going to refactor the
how-to-load language (I hadn't considered doing that, but I agree it's a
good idea), why not start doing that now saying "use kld_list unless
that host really needs the driver before loading and starting the
kernel, in which case use loader.conf) and just change that one manual
page when enough drivers are devmatch-aware?
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