i've recently added preadv2(2) and pwritev2(2) wrappers to bionic, since we
had our first real prospective user come along, and they're mildly annoying
to use via syscall(3). unfortunately, this particular user also wants to be
able to compile for the host, and our glibc is years out of date, and our
current plan is to move to musl for the host[1].

anyway ... musl doesn't have preadv2/pwritev2. i couldn't see any
discussion on the mailing list, so i thought i'd ask whether this is just
because no-one's got round to it yet, or there's some policy[2] i'm not
aware of, or what? happy to send a patch if it's just a case of "we haven't
got round to/had a need for it yet".

____
1. TL;DR: being able to statically link without worrying about licensing is
very enticing, and gets us out of a lot of the compatibility issues we have
that made our last glibc update more trouble than it was worth, and means i
have no intention of getting us embroiled in another glibc update.
2. i've been maintaining bionic for years now, and don't think i've written
down our policy explicitly. this was definitely a borderline case from the
"number of users" perspective, but for me the "annoying to use with
syscall(2)" tipped me over the edge into adding them. amusingly [or not,
depending on how you feel about "bugs you get away with"], it also made me
realize that our pread/pwrite implementations for LP64 were wrong in that
they weren't zeroing the unused half of the register pair. so that was a
bonus :-)