Imported from util/spkmodem_recv at coreboot
revision:
e70bc423f9a2e1d13827f2703efe1f9c72549f20
This is a client for spkmodem, to allow serial
console via PC speaker.
I've decided to import it in lbmk, because I
heavily modified it. The patches will be
applied next.
Signed-off-by: Leah Rowe <leah@libreboot.org>
the deleted patch (in this commit) was written to fix an
issue theoretically; it hasn't been fully tested, and some
people have reported strange issues since this patch was
merged - there is no proof that this patch causes them, but
removing this patch is the correct thing to do regardless
when nicholas added this, he removed the README because it's
going on libreboot.org instead. however, i merged a WIP version
of his page for now because i want to get the e6400 going in
libreboot sooner. so, temp-readding this README. will just
link to this on codeberg or something, from the lb docs
NOTE: I didn't write this README, hence author field set
in the commit. Nicholas wrote it, but I (Leah Rowe) am just
adding it. so, git author set to nicholas, not me
Adding it to lbmk for now as it is not yet in coreboot. If it is merged
into coreboot we can just reference the one there. The original README
will be incorporated into a new page on lbwww, so README.md just points
to a placeholder URL that should match the new page.
small nitpick, but i try to use openbsd style
since i like that style. upon further reading
of their style guidelines today, it was revealed
to me that for includes, they:
* sort sys/ includes alphabetically, at the top
* after sys/ includes, have an empty line
* includes for networking-related headers below that
* empty space below networking headers if there
* after that, have the rest of the includes, sorted
alphabetically
at least, that is my understanding. i have to admit,
it does look cleaner
not really that critical but why not do it?
don't download it. keep it in lbmk.
libreboot moved to codeberg for git hosting,
and i didn't want to keep lugging around an
extra git repo just for one tiny project.
word/setWord no longer mitigates endianness. instead,
all bytes are swapped after reading and before writing the
file, and only if the host is big endian
this improves performance on little endian hosts, which is
most machines, and the code is much simpler, so it's more
robust and less likely to break
mac address endianness made more clear in code, including
with a comment that explains it
(the nvm section contains little endian words, *except* the
mac address whose words are stored big endian)
reduce the number of calls to read() by using
bit shifts. when rnum is zero, read again. in
most cases, a nibble will not be zero, so this
will usually result in about 13-15 of of 16
nibbles being used. this is in comparison to
8 nibbles being used before, which means that
the number of calls to read() are roughly
halved. at the same time, the extra amount of
logic is minimal (and probably less) when
compiled, outside of calls to read(), because
shifting is better optimised (on 64-bit machines,
the uint64_t will be shifted with just a single
instruction, if the compiler is decent), whereas
the alternative would be to always precisely use
exactly 16 nibbles by counting up to 16, which
would involve the use of an and mask and still
need a shift, plus...
you get the point. this is probably the most
efficient code ever written, for generating
random numbers between the value of 0 and 15
the way nvmutil is designed, setWord() is only ever called
under non-error conditions. however, if one part is valid but
the other one isn't, and a command is run that touches both parts,
errno is non-zero write writeGbeFile is called
in situations where one part is valid, but the other isn't, AND the
writes to gbe (in memory) results in a non-change, writeGbeFile is
not called; in this situation, errno is not being reset, despite
non-error condition
this patch fixed the bug, resulting in zero status upon exit under
such conditions
the current code writes part 1 first, and part 0 next,
on the disk, due to the way the swap works.
with this change, swap still swaps the two parts of the file,
on disk, but writes the new file sequentially.
this change might speed up i/o on the file system, on HDDs.
on SSDs, this change likely makes no difference at all.
Leah Rowe