When I got involved with Linux-libre back in 2008, a file named
micropatch.c already existed in the Linux source tree, in
arch/powerpc/sysdev/micropatch.c. It's now in
arch/powerpc/platforms/8xx/micropatch.c.
The initial version, added back in 2007, had two sets of binary
"patches". Comments stated:
/* Microcode patches for the CPM as supplied by Motorola.
(CPM stands Communication Processor Module)
Despite the appearance that these "patches" could be code rather than
configuration data, gNewSense (and then BLAG) appear to have decided
that it could be left in, for reasons unknown to me. I assumed there
were good reasons for that, even though I didn't know them, so the
binary "patches" have remained in Linux-libre releases since then.
For most of the time, they've remained unchanged, except for
reformatting of the arrays containing them. Back in Jun 14, 2019, a new
set of binary "patches" were added. It was quite similar in appearance
and spirit, so I also retained it, assuming the same reasons applied.
Part of the commit message that introduced the new bits states:
This microcode is provided by Freescale/NXP in Engineering Bulletin
EB662 ("MPC8xx I2C/SPI and SMC Relocation Microcode Packages")
dated 2006. The binary code is public. The source is not available.
Recently, someone asked in the GNU Linux-libre discussion list why we
didn't remove these bits. I don't know the answer. I wish I did. I
find myself wondering whether it should really have been left alone.
Does anyone have any insights to share as to why this might have been
left in? Absent more information, if I were to come across it today,
I'd most certainly have removed it from Linux-libre, so I'm leaning
towards doing so in the git history rewrite project I've been slowly
working on.
thanks in advance for any information you may provide,