2df8220cc5
Kbuild builds init/built-in.a twice; first during the ordinary
directory descending, second from scripts/link-vmlinux.sh.
We do this because UTS_VERSION contains the build version and the
timestamp. We cannot update it during the normal directory traversal
since we do not yet know if we need to update vmlinux. UTS_VERSION is
temporarily calculated, but omitted from the update check. Otherwise,
vmlinux would be rebuilt every time.
When Kbuild results in running link-vmlinux.sh, it increments the
version number in the .version file and takes the timestamp at that
time to really fix UTS_VERSION.
However, updating the same file twice is a footgun. To avoid nasty
timestamp issues, all build artifacts that depend on init/built-in.a
are atomically generated in link-vmlinux.sh, where some of them do not
need rebuilding.
To fix this issue, this commit changes as follows:
[1] Split UTS_VERSION out to include/generated/utsversion.h from
include/generated/compile.h
include/generated/utsversion.h is generated just before the
vmlinux link. It is generated under include/generated/ because
some decompressors (s390, x86) use UTS_VERSION.
[2] Split init_uts_ns and linux_banner out to init/version-timestamp.c
from init/version.c
init_uts_ns and linux_banner contain UTS_VERSION. During the ordinary
directory descending, they are compiled with __weak and used to
determine if vmlinux needs relinking. Just before the vmlinux link,
they are compiled without __weak to embed the real version and
timestamp.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
56 lines
1.3 KiB
C
56 lines
1.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* linux/init/version.c
|
|
*
|
|
* Copyright (C) 1992 Theodore Ts'o
|
|
*
|
|
* May be freely distributed as part of Linux.
|
|
*/
|
|
|
|
#include <generated/compile.h>
|
|
#include <linux/build-salt.h>
|
|
#include <linux/elfnote-lto.h>
|
|
#include <linux/export.h>
|
|
#include <linux/init.h>
|
|
#include <linux/printk.h>
|
|
#include <linux/uts.h>
|
|
#include <linux/utsname.h>
|
|
#include <generated/utsrelease.h>
|
|
#include <linux/proc_ns.h>
|
|
|
|
static int __init early_hostname(char *arg)
|
|
{
|
|
size_t bufsize = sizeof(init_uts_ns.name.nodename);
|
|
size_t maxlen = bufsize - 1;
|
|
size_t arglen;
|
|
|
|
arglen = strlcpy(init_uts_ns.name.nodename, arg, bufsize);
|
|
if (arglen > maxlen) {
|
|
pr_warn("hostname parameter exceeds %zd characters and will be truncated",
|
|
maxlen);
|
|
}
|
|
return 0;
|
|
}
|
|
early_param("hostname", early_hostname);
|
|
|
|
const char linux_proc_banner[] =
|
|
"%s version %s"
|
|
" (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ")"
|
|
" (" LINUX_COMPILER ") %s\n";
|
|
|
|
BUILD_SALT;
|
|
BUILD_LTO_INFO;
|
|
|
|
/*
|
|
* init_uts_ns and linux_banner contain the build version and timestamp,
|
|
* which are really fixed at the very last step of build process.
|
|
* They are compiled with __weak first, and without __weak later.
|
|
*/
|
|
|
|
struct uts_namespace init_uts_ns __weak;
|
|
const char linux_banner[] __weak;
|
|
|
|
#include "version-timestamp.c"
|
|
|
|
EXPORT_SYMBOL_GPL(init_uts_ns);
|