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a7c699d090
The rpm-pkg make target currently suffers from a few issues related to
debuginfo:
1. debuginfo for things built into the kernel (vmlinux) is not available
in any RPM produced by make rpm-pkg. This makes using tools like
systemtap against a make rpm-pkg kernel impossible.
2. debug source for the kernel is not available. This means that
commands like 'disas /s' in gdb, which display source intermixed with
assembly, can only print file names/line numbers which then must be
painstakingly resolved to actual source in a separate editor.
3. debuginfo for modules is available, but it remains bundled with the
.ko files that contain module code, in the main kernel RPM. This is a
waste of space for users who do not need to debug the kernel (i.e.
most users).
Address all of these issues by additionally building a debuginfo RPM
when the kernel configuration allows for it, in line with standard
patterns followed by RPM distributors. With these changes:
1. systemtap now works (when these changes are backported to 6.11, since
systemtap lags a bit behind in compatibility), as verified by the
following simple test script:
# stap -e 'probe kernel.function("do_sys_open").call { printf("%s\n", $$parms); }'
dfd=0xffffffffffffff9c filename=0x7fe18800b160 flags=0x88800 mode=0x0
...
2. disas /s works correctly in gdb, with source and disassembly
interspersed:
# gdb vmlinux --batch -ex 'disas /s blk_op_str'
Dump of assembler code for function blk_op_str:
block/blk-core.c:
125 {
0xffffffff814c8740 <+0>: endbr64
127
128 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op])
0xffffffff814c8744 <+4>: mov $0xffffffff824a7378,%rax
0xffffffff814c874b <+11>: cmp $0x23,%edi
0xffffffff814c874e <+14>: ja 0xffffffff814c8768 <blk_op_str+40>
0xffffffff814c8750 <+16>: mov %edi,%edi
126 const char *op_str = "UNKNOWN";
0xffffffff814c8752 <+18>: mov $0xffffffff824a7378,%rdx
127
128 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op])
0xffffffff814c8759 <+25>: mov -0x7dfa0160(,%rdi,8),%rax
126 const char *op_str = "UNKNOWN";
0xffffffff814c8761 <+33>: test %rax,%rax
0xffffffff814c8764 <+36>: cmove %rdx,%rax
129 op_str = blk_op_name[op];
130
131 return op_str;
132 }
0xffffffff814c8768 <+40>: jmp 0xffffffff81d01360 <__x86_return_thunk>
End of assembler dump.
3. The size of the main kernel package goes down substantially,
especially if many modules are built (quite typical). Here is a
comparison of installed size of the kernel package (configured with
allmodconfig, dwarf4 debuginfo, and module compression turned off)
before and after this patch:
# rpm -qi kernel-6.13* | grep -E '^(Version|Size)'
Version : 6.13.0postpatch+
Size : 1382874089
Version : 6.13.0prepatch+
Size : 17870795887
This is a ~92% size reduction.
Note that a debuginfo package can only be produced if the following
configs are set:
- CONFIG_DEBUG_INFO=y
- CONFIG_MODULE_COMPRESS=n
- CONFIG_DEBUG_INFO_SPLIT=n
The first of these is obvious - we can't produce debuginfo if the build
does not generate it. The second two requirements can in principle be
removed, but doing so is difficult with the current approach, which uses
a generic rpmbuild script find-debuginfo.sh that processes all packaged
executables. If we want to remove those requirements the best path
forward is likely to add some debuginfo extraction/installation logic to
the modules_install target (controllable by flags). That way, it's
easier to operate on modules before they're compressed, and the logic
can be reused by all packaging targets.
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
65 lines
1.7 KiB
Bash
Executable file
65 lines
1.7 KiB
Bash
Executable file
#!/bin/sh
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#
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# Output a simple RPM spec file.
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# This version assumes a minimum of RPM 4.13
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#
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# The only gothic bit here is redefining install_post to avoid
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# stripping the symbols from files in the kernel which we want
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#
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# Patched for non-x86 by Opencon (L) 2002 <opencon@rio.skydome.net>
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#
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set -eu
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output=$1
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mkdir -p "$(dirname "${output}")"
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exec >"${output}"
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if grep -q CONFIG_MODULES=y include/config/auto.conf; then
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echo '%define with_devel %{?_without_devel: 0} %{?!_without_devel: 1}'
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else
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echo '%define with_devel 0'
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fi
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# debuginfo package generation uses find-debuginfo.sh under the hood,
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# which only works on uncompressed modules that contain debuginfo
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if grep -q CONFIG_DEBUG_INFO=y include/config/auto.conf &&
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(! grep -q CONFIG_MODULE_COMPRESS=y include/config/auto.conf) &&
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(! grep -q CONFIG_DEBUG_INFO_SPLIT=y include/config/auto.conf); then
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echo '%define with_debuginfo %{?_without_debuginfo: 0} %{?!_without_debuginfo: 1}'
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else
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echo '%define with_debuginfo 0'
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fi
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cat<<EOF
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%define ARCH ${ARCH}
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%define KERNELRELEASE ${KERNELRELEASE}
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%define pkg_release $("${srctree}/scripts/build-version")
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EOF
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cat "${srctree}/scripts/package/kernel.spec"
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# collect the user's name and email address for the changelog entry
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if [ "$(command -v git)" ]; then
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name=$(git config user.name) || true
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email=$(git config user.email) || true
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fi
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if [ ! "${name:+set}" ]; then
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name=${KBUILD_BUILD_USER:-$(id -nu)}
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fi
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if [ ! "${email:+set}" ]; then
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buildhost=${KBUILD_BUILD_HOST:-$(hostname -f 2>/dev/null || hostname)}
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builduser=${KBUILD_BUILD_USER:-$(id -nu)}
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email="${builduser}@${buildhost}"
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fi
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cat << EOF
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%changelog
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* $(LC_ALL=C date +'%a %b %d %Y') ${name} <${email}>
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- Custom built Linux kernel.
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EOF
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