[PATCH] rust: Prefer link_with over link_whole

[PATCH] rust: Prefer link_with over link_whole

[Zhao Liu]

The commit fccb744f41c6 ("gdbstub: Try unlinking the unix socket before
binding") causes the compilation of rust-qemu-api-integration to fail,
because rust-qemu-api-integration uses link_whole which meets the
duplicate symbol linker error.

Though it's not the issue of link_whole used by Rust side, there's no
need to use link_whole.

Use link_with, which may also bring some benefits, such as faster
linking or smaller output files.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
 rust/hw/char/pl011/meson.build | 2 +-
 rust/hw/timer/hpet/meson.build | 2 +-
 rust/qemu-api/meson.build      | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/rust/hw/char/pl011/meson.build b/rust/hw/char/pl011/meson.build
index 547cca5a96f7..4ba9089fcf8e 100644
--- a/rust/hw/char/pl011/meson.build
+++ b/rust/hw/char/pl011/meson.build
@@ -18,7 +18,7 @@ _libpl011_rs = static_library(
 )
 
 rust_devices_ss.add(when: 'CONFIG_X_PL011_RUST', if_true: [declare_dependency(
-  link_whole: [_libpl011_rs],
+  link_with: [_libpl011_rs],
   # Putting proc macro crates in `dependencies` is necessary for Meson to find
   # them when compiling the root per-target static rust lib.
   dependencies: [bilge_impl_dep, qemu_api_macros],
diff --git a/rust/hw/timer/hpet/meson.build b/rust/hw/timer/hpet/meson.build
index c2d7c0532ca4..ce90cc4f021a 100644
--- a/rust/hw/timer/hpet/meson.build
+++ b/rust/hw/timer/hpet/meson.build
@@ -10,7 +10,7 @@ _libhpet_rs = static_library(
 )
 
 rust_devices_ss.add(when: 'CONFIG_X_HPET_RUST', if_true: [declare_dependency(
-  link_whole: [_libhpet_rs],
+  link_with: [_libhpet_rs],
   # Putting proc macro crates in `dependencies` is necessary for Meson to find
   # them when compiling the root per-target static rust lib.
   dependencies: [qemu_api_macros],
diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build
index 2e9c1078b9b2..e825671b694b 100644
--- a/rust/qemu-api/meson.build
+++ b/rust/qemu-api/meson.build
@@ -63,7 +63,7 @@ test('rust-qemu-api-integration',
         rust_args: ['--test'],
         install: false,
         dependencies: [qemu_api, qemu_api_macros],
-        link_whole: [rust_qemu_api_objs, libqemuutil]),
+        link_with: [rust_qemu_api_objs, libqemuutil]),
     args: [
         '--test', '--test-threads', '1',
         '--format', 'pretty',
-- 
2.34.1

Re: [PATCH] rust: Prefer link_with over link_whole

[Paolo Bonzini]

On 2/18/25 09:37, Zhao Liu wrote:
> The commit fccb744f41c6 ("gdbstub: Try unlinking the unix socket before
> binding") causes the compilation of rust-qemu-api-integration to fail,
> because rust-qemu-api-integration uses link_whole which meets the
> duplicate symbol linker error.
> 
> Though it's not the issue of link_whole used by Rust side, there's no
> need to use link_whole.
> 
> Use link_with, which may also bring some benefits, such as faster
> linking or smaller output files.

link_with, if I remember correctly, drops the constructors.  Using it in 
rust_devices_ss therefore prevents the devices from being registered 
with QOM.

The real issue is lack of support for "objects" in Meson for Rust 
executables.  A patch to fix that is under review, after which it will 
be possible to build Rust executables using the same "dependency" 
objects as C code.

Paolo

>   rust_devices_ss.add(when: 'CONFIG_X_PL011_RUST', if_true: [declare_dependency(
> -  link_whole: [_libpl011_rs],
> +  link_with: [_libpl011_rs],
>     # Putting proc macro crates in `dependencies` is necessary for Meson to find
>     # them when compiling the root per-target static rust lib.
>     dependencies: [bilge_impl_dep, qemu_api_macros],
> diff --git a/rust/hw/timer/hpet/meson.build b/rust/hw/timer/hpet/meson.build
> index c2d7c0532ca4..ce90cc4f021a 100644
> --- a/rust/hw/timer/hpet/meson.build
> +++ b/rust/hw/timer/hpet/meson.build
> @@ -10,7 +10,7 @@ _libhpet_rs = static_library(
>   )
>   
>   rust_devices_ss.add(when: 'CONFIG_X_HPET_RUST', if_true: [declare_dependency(
> -  link_whole: [_libhpet_rs],
> +  link_with: [_libhpet_rs],
>     # Putting proc macro crates in `dependencies` is necessary for Meson to find
>     # them when compiling the root per-target static rust lib.
>     dependencies: [qemu_api_macros],
> diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build
> index 2e9c1078b9b2..e825671b694b 100644
> --- a/rust/qemu-api/meson.build
> +++ b/rust/qemu-api/meson.build
> @@ -63,7 +63,7 @@ test('rust-qemu-api-integration',
>           rust_args: ['--test'],
>           install: false,
>           dependencies: [qemu_api, qemu_api_macros],
> -        link_whole: [rust_qemu_api_objs, libqemuutil]),
> +        link_with: [rust_qemu_api_objs, libqemuutil]),
>       args: [
>           '--test', '--test-threads', '1',
>           '--format', 'pretty',

Re: [PATCH] rust: Prefer link_with over link_whole

[Zhao Liu]

On Tue, Feb 18, 2025 at 09:58:44AM +0100, Paolo Bonzini wrote:
> Date: Tue, 18 Feb 2025 09:58:44 +0100
> From: Paolo Bonzini <pbonzini@redhat.com>
> Subject: Re: [PATCH] rust: Prefer link_with over link_whole
> 
> On 2/18/25 09:37, Zhao Liu wrote:
> > The commit fccb744f41c6 ("gdbstub: Try unlinking the unix socket before
> > binding") causes the compilation of rust-qemu-api-integration to fail,
> > because rust-qemu-api-integration uses link_whole which meets the
> > duplicate symbol linker error.
> > 
> > Though it's not the issue of link_whole used by Rust side, there's no
> > need to use link_whole.
> > 
> > Use link_with, which may also bring some benefits, such as faster
> > linking or smaller output files.
> 
> link_with, if I remember correctly, drops the constructors.  Using it in
> rust_devices_ss therefore prevents the devices from being registered with
> QOM.

Interesting, I test with link_with and HPET QOM type can be registered.

I find this is because `module_init` macro adds `#[used]` for `LOAD_MODULE`,
which prevents linker dropping QOM type.

Without `#[used]`, both link_with and link_whole will optimize
`LOAD_MODULE`... So here `#[used]` is the key to getting everything to work
properly.

> The real issue is lack of support for "objects" in Meson for Rust
> executables.  A patch to fix that is under review, after which it will be
> possible to build Rust executables using the same "dependency" objects as C
> code.

HMM, but with link_with, everything seems to compile fine?

Thanks,
Zhao