[PATCH 0/9] (mostly) x86 kernel configuration adjustments
Elliott Mitchell
ehem+openwrt at m5p.com
Wed Apr 26 13:11:51 PDT 2023
I've been mentioning the issue several times, but the OpenWRT x86 builds
really don't seem to fit well. As such several x86 kernel configuration
adjustments I think are appropriate.
First, a side issue. The "# CONFIG_<name> is not set" was meant for use
by tools. Theory being almost all options would default to "no"
therefore this implied the person doing configuration had left them
alone. Setting an option to "n" is more common when configurations are
handled manually. Most tools work perfectly with this and I suggest
this should be preferred, when appropriate, going forward.
First up is the simple observation CONFIG_FB_NOTIFY disappeared at some
point. Since it no longer does anything, the setting should be purged.
Next up is some bits related to hardware random-number generators. I
notice rather more kernel configuration files set CONFIG_HW_RANDOM to yes
than set it to no. As such having the default be yes is a win. Right
now this is a mild improvement, but HW RNGs are becoming more common so
this should improve over time.
I also found support for the Geode HW random number generator had gotten
into the common x86 configuration. I imagine having the support is
advantageous to Geode devices. Anything else it is disadvantageous.
What originally brought the Geode HW RNG situation to my attention was
noticing CONFIG_SCx200. Appears CONFIG_SCx200 is part of the Geode
platform. Similar to the previous I don't doubt Geode systems need the
driver. Non-Geode x86 though simply don't.
Appears the architecture type CONFIG_M<proc> values need to be set to
something. They should all be unset in the common file though. All of
the subtargets explicitly specify some processor.
Now we come to the item I've mentioned. The X32 ABI. This is running an
amd64 processor in amd64 mode, but truncating all pointers to 32 bits
(ILP32 mode). This shrinks the runtime size of programs in exchange for
limiting them to a maximum of 4GB of memory. The result is often a
significant speed increase over both i386 and amd64 modes, largely due to
reducing memory use.
For rather a lot of programs, 4GB of memory is plenty. Have you ever
observed `ls` or a shell use anywhere near that much? The fact most
devices running OpenWRT don't have that much *total* memory says the
limitation is worthwhile.
The difficulty is this means bringing up a new toolchain. While the
deltas are small, compilers, linkers and libc all need minor
adjustments.
The other question is whether to have separate amd64 (or "64") and
x32 builds, versus a single combined one.
Looks like little of ISA remained on "64", yet some DMA support remained
due to the generic configuration. Remove the ISA and ISA DMA support
from the top-level configuration. Geode and Legacy though almost
certainly still need ISA support.
In case someone doesn't know, "AGP" is short for "Accelerated Graphics
Port". This was an interim standard when graphics cards in the late
1990s were overwhelming PCI, but PCI-Express wasn't yet available. Since
OpenWRT is a router distribution, this doesn't seem like a good fit. If
you've got such an Intel board, this will reduce graphics performance,
but will release ~.5MB extra memory for better uses.
The Direct Rendering Manager was created in association with XFree86.
The goal was making graphics faster and moving some things which had been
implemented in XFree86, but really needed to be in the kernel into the
kernel. I suspect Wayland may well depend on some or all of this. Yet
isn't OpenWRT's target embedded network devices? This is something
needed for a graphics desktop, not an embedded networking devices (unless
you're trying to create X-terminals). As such this also seems like a
misfit for OpenWRT/x86.
Elliott Mitchell (9):
kernel/generic: remove CONFIG_FB_NOTIFY
kernel: change CONFIG_HW_RANDOM default to y
kernel/x86: move Geode HW random from generic to geode
kernel/x86: move SCx200 support from generic to geode
kernel/x86: remove CONFIG_M686 from common configuration
kernel/x86: enable x32 support for amd64
kernel/x86: remove all ISA support from non-legacy
kernel/x86: remove support for AGP
kernel/x86: remove DRM support
target/linux/airoha/config-5.15 | 1 -
target/linux/apm821xx/config-5.10 | 1 -
target/linux/apm821xx/config-5.15 | 1 -
target/linux/archs38/config-5.10 | 1 +
target/linux/archs38/config-5.15 | 1 +
target/linux/armvirt/32/config-5.10 | 1 +
target/linux/armvirt/32/config-5.15 | 1 +
target/linux/armvirt/64/config-5.10 | 1 -
target/linux/armvirt/64/config-5.15 | 1 -
target/linux/ath25/config-5.10 | 1 -
target/linux/ath79/config-5.10 | 1 +
target/linux/ath79/config-5.15 | 1 +
target/linux/bcm47xx/config-5.10 | 1 -
target/linux/bcm47xx/config-5.15 | 1 -
target/linux/bcm4908/config-5.10 | 1 +
target/linux/bcm4908/config-5.15 | 1 +
target/linux/bcm53xx/config-5.10 | 1 -
target/linux/bcm53xx/config-5.15 | 1 -
target/linux/bcm63xx/config-5.15 | 1 -
target/linux/gemini/config-5.10 | 1 +
target/linux/gemini/config-5.15 | 1 -
target/linux/generic/config-5.10 | 3 +-
target/linux/generic/config-5.15 | 3 +-
target/linux/imx/config-5.15 | 1 -
target/linux/ipq40xx/config-5.15 | 1 -
target/linux/ipq806x/config-5.10 | 1 -
target/linux/ipq806x/config-5.15 | 1 -
target/linux/ipq807x/config-5.15 | 1 +
target/linux/kirkwood/config-5.10 | 1 -
target/linux/kirkwood/config-5.15 | 1 -
target/linux/lantiq/ase/config-5.10 | 1 -
target/linux/lantiq/ase/config-5.15 | 1 -
target/linux/lantiq/falcon/config-5.10 | 1 +
target/linux/lantiq/falcon/config-5.15 | 1 +
target/linux/lantiq/xrx200/config-5.10 | 1 -
target/linux/lantiq/xrx200/config-5.15 | 1 -
target/linux/lantiq/xway/config-5.10 | 1 -
target/linux/lantiq/xway/config-5.15 | 1 -
target/linux/lantiq/xway_legacy/config-5.10 | 1 +
target/linux/lantiq/xway_legacy/config-5.15 | 1 +
target/linux/malta/config-5.10 | 1 +
target/linux/malta/config-5.15 | 1 +
target/linux/mpc85xx/config-5.10 | 1 -
target/linux/mpc85xx/config-5.15 | 1 -
target/linux/mvebu/config-5.10 | 1 -
target/linux/mvebu/config-5.15 | 1 -
target/linux/mxs/config-5.15 | 1 +
target/linux/octeon/config-5.10 | 1 -
target/linux/octeon/config-5.15 | 1 -
target/linux/octeontx/config-5.15 | 1 -
target/linux/omap/config-5.10 | 1 -
target/linux/omap/config-5.15 | 1 -
target/linux/oxnas/config-5.15 | 1 +
target/linux/pistachio/config-5.10 | 1 +
target/linux/pistachio/config-5.15 | 1 +
target/linux/qoriq/config-5.15 | 1 -
target/linux/sunxi/config-5.15 | 1 -
target/linux/tegra/config-5.10 | 1 +
target/linux/tegra/config-5.15 | 1 +
target/linux/uml/config-5.10 | 1 -
target/linux/uml/config-5.15 | 1 -
target/linux/x86/64/config-5.10 | 46 ------------------
target/linux/x86/64/config-5.15 | 46 ------------------
target/linux/x86/config-5.10 | 16 +++---
target/linux/x86/config-5.15 | 16 +++---
target/linux/x86/generic/config-5.10 | 51 -------------------
target/linux/x86/generic/config-5.15 | 51 -------------------
target/linux/x86/geode/config-5.10 | 8 ++-
target/linux/x86/geode/config-5.15 | 8 ++-
target/linux/x86/legacy/config-5.10 | 54 +--------------------
target/linux/x86/legacy/config-5.15 | 54 +--------------------
target/linux/zynq/config-5.15 | 1 +
72 files changed, 55 insertions(+), 361 deletions(-)
--
(\___(\___(\______ --=> 8-) EHM <=-- ______/)___/)___/)
\BS ( | ehem+openwrt at m5p.com PGP 87145445 | ) /
\_CS\ | _____ -O #include <stddisclaimer.h> O- _____ | / _/
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