| Message ID | 20250306105306.2064458-1-alex.bennee@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] meson.build: default to -gsplit-dwarf for debug info | expand |
On Thu, Mar 06, 2025 at 10:53:06AM +0000, Alex Bennée wrote: > This option is supported by both gcc (since 4.7) and clang (since > 7.0). Not only does this make the linkers job easier by reducing the > amount of ELF it needs to parse it also reduces the total build size > quite considerably. In my case a default build went from 5.8G to 3.9G. > > The --disable-split-debug option allows distros to keep all the info > together for ease of packaging. > > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> > > --- > v1 > - add --disable/enable-split-debug > - move to option_cflags > v2 > - removed unneeded []'s > - fix stray whitespace > --- > meson.build | 5 ++++- > meson_options.txt | 2 ++ > scripts/meson-buildoptions.sh | 2 ++ > 3 files changed, 8 insertions(+), 1 deletion(-) Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> With regards, Daniel
Il gio 6 mar 2025, 11:53 Alex Bennée <alex.bennee@linaro.org> ha scritto: > -option_cflags = (get_option('debug') ? ['-g'] : []) > +option_cflags = [] > +if get_option('debug') > + option_cflags += get_option('split_debug') ? ['-gsplit-dwarf'] : ['-g'] > +endif > option_cflags does nothing, it's only for clarity in the final summary. So you need if get_option('debug') and get_option('split_debug') qemu_cflags += '-gsplit-dwarf' endif (I wonder if it should be implemented in meson instead... It should be beneficial for other projects surely). Paolo if get_option('optimization') != 'plain' > option_cflags += ['-O' + get_option('optimization')] > endif > diff --git a/meson_options.txt b/meson_options.txt > index 59d973bca0..3432123fee 100644 > --- a/meson_options.txt > +++ b/meson_options.txt > @@ -362,6 +362,8 @@ option('debug_mutex', type: 'boolean', value: false, > description: 'mutex debugging support') > option('debug_stack_usage', type: 'boolean', value: false, > description: 'measure coroutine stack usage') > +option('split_debug', type: 'boolean', value: true, > + description: 'split debug info from object files') > option('qom_cast_debug', type: 'boolean', value: true, > description: 'cast debugging support') > option('slirp_smbd', type : 'feature', value : 'auto', > diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh > index 3e8e00852b..aca6e68830 100644 > --- a/scripts/meson-buildoptions.sh > +++ b/scripts/meson-buildoptions.sh > @@ -504,6 +504,8 @@ _meson_option_parse() { > --disable-strict-rust-lints) printf "%s" -Dstrict_rust_lints=false ;; > --enable-strip) printf "%s" -Dstrip=true ;; > --disable-strip) printf "%s" -Dstrip=false ;; > + --enable-split-debug) printf "%s" -Dsplit_debug=true ;; > + --disable-split-debug) printf "%s" -Dsplit_debug=false ;; > --sysconfdir=*) quote_sh "-Dsysconfdir=$2" ;; > --enable-tcg) printf "%s" -Dtcg=enabled ;; > --disable-tcg) printf "%s" -Dtcg=disabled ;; > -- > 2.39.5 > >
Paolo Bonzini <pbonzini@redhat.com> writes: > Il gio 6 mar 2025, 11:53 Alex Bennée <alex.bennee@linaro.org> ha scritto: > > -option_cflags = (get_option('debug') ? ['-g'] : []) > +option_cflags = [] > +if get_option('debug') > + option_cflags += get_option('split_debug') ? ['-gsplit-dwarf'] : ['-g'] > +endif > > option_cflags does nothing, it's only for clarity in the final summary. So you need > > if get_option('debug') and get_option('split_debug') > qemu_cflags += '-gsplit-dwarf' > endif Should I update the optimization field as well? is this the reason why I wasn't seeing changes occur for the tests that meson builds? > > (I wonder if it should be implemented in meson instead... It should be beneficial for other projects surely). > > Paolo > > if get_option('optimization') != 'plain' > option_cflags += ['-O' + get_option('optimization')] > endif > diff --git a/meson_options.txt b/meson_options.txt > index 59d973bca0..3432123fee 100644 > --- a/meson_options.txt > +++ b/meson_options.txt > @@ -362,6 +362,8 @@ option('debug_mutex', type: 'boolean', value: false, > description: 'mutex debugging support') > option('debug_stack_usage', type: 'boolean', value: false, > description: 'measure coroutine stack usage') > +option('split_debug', type: 'boolean', value: true, > + description: 'split debug info from object files') > option('qom_cast_debug', type: 'boolean', value: true, > description: 'cast debugging support') > option('slirp_smbd', type : 'feature', value : 'auto', > diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh > index 3e8e00852b..aca6e68830 100644 > --- a/scripts/meson-buildoptions.sh > +++ b/scripts/meson-buildoptions.sh > @@ -504,6 +504,8 @@ _meson_option_parse() { > --disable-strict-rust-lints) printf "%s" -Dstrict_rust_lints=false ;; > --enable-strip) printf "%s" -Dstrip=true ;; > --disable-strip) printf "%s" -Dstrip=false ;; > + --enable-split-debug) printf "%s" -Dsplit_debug=true ;; > + --disable-split-debug) printf "%s" -Dsplit_debug=false ;; > --sysconfdir=*) quote_sh "-Dsysconfdir=$2" ;; > --enable-tcg) printf "%s" -Dtcg=enabled ;; > --disable-tcg) printf "%s" -Dtcg=disabled ;; > -- > 2.39.5
Il gio 6 mar 2025, 13:20 Alex Bennée <alex.bennee@linaro.org> ha scritto: > Paolo Bonzini <pbonzini@redhat.com> writes: > > > Il gio 6 mar 2025, 11:53 Alex Bennée <alex.bennee@linaro.org> ha > scritto: > > > > -option_cflags = (get_option('debug') ? ['-g'] : []) > > +option_cflags = [] > > +if get_option('debug') > > + option_cflags += get_option('split_debug') ? ['-gsplit-dwarf'] : > ['-g'] > > +endif > > > > option_cflags does nothing, it's only for clarity in the final summary. > So you need > > > > if get_option('debug') and get_option('split_debug') > > qemu_cflags += '-gsplit-dwarf' > > endif > > Should I update the optimization field as well? is this the reason why I > wasn't seeing changes occur for the tests that meson builds? > I am not sure what you mean by optimization field; anyway, qemu_cflags applies to all C sources and qemu_ldflags to all programs linked with the C compiler. As I understand it, '-gsplit-dwarf' should go in qemu_cflags. Paolo > > > > (I wonder if it should be implemented in meson instead... It should be > beneficial for other projects surely). > > > > Paolo > > > > if get_option('optimization') != 'plain' > > option_cflags += ['-O' + get_option('optimization')] > > endif > > diff --git a/meson_options.txt b/meson_options.txt > > index 59d973bca0..3432123fee 100644 > > --- a/meson_options.txt > > +++ b/meson_options.txt > > @@ -362,6 +362,8 @@ option('debug_mutex', type: 'boolean', value: false, > > description: 'mutex debugging support') > > option('debug_stack_usage', type: 'boolean', value: false, > > description: 'measure coroutine stack usage') > > +option('split_debug', type: 'boolean', value: true, > > + description: 'split debug info from object files') > > option('qom_cast_debug', type: 'boolean', value: true, > > description: 'cast debugging support') > > option('slirp_smbd', type : 'feature', value : 'auto', > > diff --git a/scripts/meson-buildoptions.sh > b/scripts/meson-buildoptions.sh > > index 3e8e00852b..aca6e68830 100644 > > --- a/scripts/meson-buildoptions.sh > > +++ b/scripts/meson-buildoptions.sh > > @@ -504,6 +504,8 @@ _meson_option_parse() { > > --disable-strict-rust-lints) printf "%s" -Dstrict_rust_lints=false > ;; > > --enable-strip) printf "%s" -Dstrip=true ;; > > --disable-strip) printf "%s" -Dstrip=false ;; > > + --enable-split-debug) printf "%s" -Dsplit_debug=true ;; > > + --disable-split-debug) printf "%s" -Dsplit_debug=false ;; > > --sysconfdir=*) quote_sh "-Dsysconfdir=$2" ;; > > --enable-tcg) printf "%s" -Dtcg=enabled ;; > > --disable-tcg) printf "%s" -Dtcg=disabled ;; > > -- > > 2.39.5 > > -- > Alex Bennée > Virtualisation Tech Lead @ Linaro > >
Paolo Bonzini <pbonzini@redhat.com> writes: > Il gio 6 mar 2025, 13:20 Alex Bennée <alex.bennee@linaro.org> ha scritto: > > Paolo Bonzini <pbonzini@redhat.com> writes: > > > Il gio 6 mar 2025, 11:53 Alex Bennée <alex.bennee@linaro.org> ha scritto: > > > > -option_cflags = (get_option('debug') ? ['-g'] : []) > > +option_cflags = [] > > +if get_option('debug') > > + option_cflags += get_option('split_debug') ? ['-gsplit-dwarf'] : ['-g'] > > +endif > > > > option_cflags does nothing, it's only for clarity in the final summary. So you need > > > > if get_option('debug') and get_option('split_debug') > > qemu_cflags += '-gsplit-dwarf' > > endif > > Should I update the optimization field as well? is this the reason why I > wasn't seeing changes occur for the tests that meson builds? > > I am not sure what you mean by optimization field; anyway, qemu_cflags applies to all C sources and qemu_ldflags to all > programs linked with the C compiler. As I understand it, > '-gsplit-dwarf' should go in qemu_cflags. if get_option('optimization') != 'plain' option_cflags += ['-O' + get_option('optimization')] endif Are you saying this is never applied to the build? > > Paolo > > > > > (I wonder if it should be implemented in meson instead... It should be beneficial for other projects surely). > > > > Paolo > > > > if get_option('optimization') != 'plain' > > option_cflags += ['-O' + get_option('optimization')] > > endif > > diff --git a/meson_options.txt b/meson_options.txt > > index 59d973bca0..3432123fee 100644 > > --- a/meson_options.txt > > +++ b/meson_options.txt > > @@ -362,6 +362,8 @@ option('debug_mutex', type: 'boolean', value: false, > > description: 'mutex debugging support') > > option('debug_stack_usage', type: 'boolean', value: false, > > description: 'measure coroutine stack usage') > > +option('split_debug', type: 'boolean', value: true, > > + description: 'split debug info from object files') > > option('qom_cast_debug', type: 'boolean', value: true, > > description: 'cast debugging support') > > option('slirp_smbd', type : 'feature', value : 'auto', > > diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh > > index 3e8e00852b..aca6e68830 100644 > > --- a/scripts/meson-buildoptions.sh > > +++ b/scripts/meson-buildoptions.sh > > @@ -504,6 +504,8 @@ _meson_option_parse() { > > --disable-strict-rust-lints) printf "%s" -Dstrict_rust_lints=false ;; > > --enable-strip) printf "%s" -Dstrip=true ;; > > --disable-strip) printf "%s" -Dstrip=false ;; > > + --enable-split-debug) printf "%s" -Dsplit_debug=true ;; > > + --disable-split-debug) printf "%s" -Dsplit_debug=false ;; > > --sysconfdir=*) quote_sh "-Dsysconfdir=$2" ;; > > --enable-tcg) printf "%s" -Dtcg=enabled ;; > > --disable-tcg) printf "%s" -Dtcg=disabled ;; > > -- > > 2.39.5 > > -- > Alex Bennée > Virtualisation Tech Lead @ Linaro
diff --git a/meson.build b/meson.build index 8d0abe7f12..09e34a6d63 100644 --- a/meson.build +++ b/meson.build @@ -4589,7 +4589,10 @@ if have_rust summary_info += {'bindgen': bindgen.full_path()} summary_info += {'bindgen version': bindgen.version()} endif -option_cflags = (get_option('debug') ? ['-g'] : []) +option_cflags = [] +if get_option('debug') + option_cflags += get_option('split_debug') ? ['-gsplit-dwarf'] : ['-g'] +endif if get_option('optimization') != 'plain' option_cflags += ['-O' + get_option('optimization')] endif diff --git a/meson_options.txt b/meson_options.txt index 59d973bca0..3432123fee 100644 --- a/meson_options.txt +++ b/meson_options.txt @@ -362,6 +362,8 @@ option('debug_mutex', type: 'boolean', value: false, description: 'mutex debugging support') option('debug_stack_usage', type: 'boolean', value: false, description: 'measure coroutine stack usage') +option('split_debug', type: 'boolean', value: true, + description: 'split debug info from object files') option('qom_cast_debug', type: 'boolean', value: true, description: 'cast debugging support') option('slirp_smbd', type : 'feature', value : 'auto', diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh index 3e8e00852b..aca6e68830 100644 --- a/scripts/meson-buildoptions.sh +++ b/scripts/meson-buildoptions.sh @@ -504,6 +504,8 @@ _meson_option_parse() { --disable-strict-rust-lints) printf "%s" -Dstrict_rust_lints=false ;; --enable-strip) printf "%s" -Dstrip=true ;; --disable-strip) printf "%s" -Dstrip=false ;; + --enable-split-debug) printf "%s" -Dsplit_debug=true ;; + --disable-split-debug) printf "%s" -Dsplit_debug=false ;; --sysconfdir=*) quote_sh "-Dsysconfdir=$2" ;; --enable-tcg) printf "%s" -Dtcg=enabled ;; --disable-tcg) printf "%s" -Dtcg=disabled ;;
This option is supported by both gcc (since 4.7) and clang (since 7.0). Not only does this make the linkers job easier by reducing the amount of ELF it needs to parse it also reduces the total build size quite considerably. In my case a default build went from 5.8G to 3.9G. The --disable-split-debug option allows distros to keep all the info together for ease of packaging. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> --- v1 - add --disable/enable-split-debug - move to option_cflags v2 - removed unneeded []'s - fix stray whitespace --- meson.build | 5 ++++- meson_options.txt | 2 ++ scripts/meson-buildoptions.sh | 2 ++ 3 files changed, 8 insertions(+), 1 deletion(-)