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Message-Id: <20240131104851.2311358-1-john.g.garry@oracle.com>
Date: Wed, 31 Jan 2024 10:48:47 +0000
From: John Garry <john.g.garry@...cle.com>
To: mcgrof@...nel.org, russ.weight@...ux.dev, gregkh@...uxfoundation.org,
rafael@...nel.org, rostedt@...dmis.org, mhiramat@...nel.org,
mathieu.desnoyers@...icios.com, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
keescook@...omium.org, masahiroy@...nel.org, nathan@...nel.org,
nicolas@...sle.eu
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
netdev@...r.kernel.org, linux-kbuild@...r.kernel.org,
John Garry <john.g.garry@...cle.com>
Subject: [PATCH RFC 0/4] Introduce uts_release
When hacking it is a waste of time and compute energy that we need to
rebuild much kernel code just for changing the head git commit, like this:
> touch include/generated/utsrelease.h
> time make -j3
mkdir -p /home/john/mnt_sda4/john/kernel-dev2/tools/objtool && make O=/home/john/mnt_sda4/john/kernel-dev2 subdir=tools/objtool --no-print-directory -C objtool
INSTALL libsubcmd_headers
CALL scripts/checksyscalls.sh
CC init/version.o
AR init/built-in.a
CC kernel/sys.o
CC kernel/module/main.o
AR kernel/module/built-in.a
CC drivers/base/firmware_loader/main.o
CC kernel/trace/trace.o
AR drivers/base/firmware_loader/built-in.a
AR drivers/base/built-in.a
CC net/ethtool/ioctl.o
AR kernel/trace/built-in.a
AR kernel/built-in.a
AR net/ethtool/built-in.a
AR net/built-in.a
AR drivers/built-in.a
AR built-in.a
...
Files like drivers/base/firmware_loader/main.c needs to be recompiled as
it includes generated/utsrelease.h for UTS_RELEASE macro, and utsrelease.h
is regenerated when the head commit changes.
Introduce global char uts_release[] in init/version.c, which this
mentioned code can use instead of UTS_RELEASE, meaning that we don't need
to rebuild for changing the head commit - only init/version.c needs to be
rebuilt. Whether all the references to UTS_RELEASE in the codebase are
proper is a different matter.
For an x86_64 defconfig build for this series on my old laptop, here is
before and after rebuild time:
before:
real 0m53.591s
user 1m1.842s
sys 0m9.161s
after:
real 0m37.481s
user 0m46.461s
sys 0m7.199s
Sending as an RFC as I need to test more of the conversions and I would
like to also convert more UTS_RELEASE users to prove this is proper
approach.
John Garry (4):
init: Add uts_release
tracing: Use uts_release
net: ethtool: Use uts_release
firmware_loader: Use uts_release
drivers/base/firmware_loader/main.c | 39 +++++++++++++++++++++++------
include/linux/utsname.h | 1 +
init/version.c | 3 +++
kernel/trace/trace.c | 4 +--
net/ethtool/ioctl.c | 4 +--
5 files changed, 39 insertions(+), 12 deletions(-)
--
2.35.3
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