Problems with building vhost-device-sound in musl

[epilys]

          Setting `export PKG_CONFIG_ALLOW_CROSS=1` was enough to get through that, but:

1. I can't build pipewire with musl, it complains stdbool.h is missing. I tried installing musl-dev and setting the library path to musl's dir in .cargo/config.toml:

   [target.x86_64-unknown-linux-musl]
   linker = "ld"
   rustflags = ["-Ctarget-feature=-crt-static", "-Clink-self-contained=on", "-L/usr/lib/x86_64-linux-musl", "-Clink-args=--dynamic-linker /lib/ld-musl-x86_64.so.1"]

   but no dice. Any ideas?

2. Disabling default features with --no-default-features gives me errors from rust-vmm crates:

Compilation errors..

   Compiling vhost-user-backend v0.10.1
error[E0277]: the trait bound `<M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory` is not satisfied
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vhost-user-backend-0.10.1/src/vring.rs:145:23
    |
145 |             .add_used(self.mem.memory().deref(), desc_index, len)
    |              -------- ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `vm_memory::guest_memory::GuestMemory` is not implemented for `<M as GuestAddressSpace>::M`
    |              |
    |              required by a bound introduced by this call
    |
note: required by a bound in `add_used`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/virtio-queue-0.9.1/src/lib.rs:193:20
    |
193 |     fn add_used<M: GuestMemory>(&mut self, mem: &M, head_index: u16, len: u32)
    |                    ^^^^^^^^^^^ required by this bound in `QueueT::add_used`
help: consider further restricting the associated type
    |
143 |     pub fn add_used(&mut self, desc_index: u16, len: u32) -> Result<(), VirtQueError> where <M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory {
    |                                                                                       +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

error[E0277]: the trait bound `<M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory` is not satisfied
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vhost-user-backend-0.10.1/src/vring.rs:159:40
    |
159 |         self.queue.enable_notification(self.mem.memory().deref())
    |                    ------------------- ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `vm_memory::guest_memory::GuestMemory` is not implemented for `<M as GuestAddressSpace>::M`
    |                    |
    |                    required by a bound introduced by this call
    |
note: required by a bound in `enable_notification`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/virtio-queue-0.9.1/src/lib.rs:201:31
    |
201 |     fn enable_notification<M: GuestMemory>(&mut self, mem: &M) -> Result<bool, Error>;
    |                               ^^^^^^^^^^^ required by this bound in `QueueT::enable_notification`
help: consider further restricting the associated type
    |
158 |     pub fn enable_notification(&mut self) -> Result<bool, VirtQueError> where <M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory {
    |                                                                         +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

error[E0277]: the trait bound `<M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory` is not satisfied
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vhost-user-backend-0.10.1/src/vring.rs:164:41
    |
164 |         self.queue.disable_notification(self.mem.memory().deref())
    |                    -------------------- ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `vm_memory::guest_memory::GuestMemory` is not implemented for `<M as GuestAddressSpace>::M`
    |                    |
    |                    required by a bound introduced by this call
    |
note: required by a bound in `disable_notification`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/virtio-queue-0.9.1/src/lib.rs:204:32
    |
204 |     fn disable_notification<M: GuestMemory>(&mut self, mem: &M) -> Result<(), Error>;
    |                                ^^^^^^^^^^^ required by this bound in `QueueT::disable_notification`
help: consider further restricting the associated type
    |
163 |     pub fn disable_notification(&mut self) -> Result<(), VirtQueError> where <M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory {
    |                                                                        +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

error[E0277]: the trait bound `<M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory` is not satisfied
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vhost-user-backend-0.10.1/src/vring.rs:169:39
    |
169 |         self.queue.needs_notification(self.mem.memory().deref())
    |                    ------------------ ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `vm_memory::guest_memory::GuestMemory` is not implemented for `<M as GuestAddressSpace>::M`
    |                    |
    |                    required by a bound introduced by this call
    |
note: required by a bound in `needs_notification`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/virtio-queue-0.9.1/src/lib.rs:212:30
    |
212 |     fn needs_notification<M: GuestMemory>(&mut self, mem: &M) -> Result<bool, Error>;
    |                              ^^^^^^^^^^^ required by this bound in `QueueT::needs_notification`
help: consider further restricting the associated type
    |
168 |     pub fn needs_notification(&mut self) -> Result<bool, VirtQueError> where <M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory {
    |                                                                        +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

error[E0308]: mismatched types
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vhost-user-backend-0.10.1/src/vring.rs:185:41
    |
185 |             .try_set_desc_table_address(GuestAddress(desc_table))?;
    |              -------------------------- ^^^^^^^^^^^^^^^^^^^^^^^^ expected `GuestAddress`, found a different `GuestAddress`
    |              |
    |              arguments to this method are incorrect
    |
    = note: `GuestAddress` and `GuestAddress` have similar names, but are actually distinct types
note: `GuestAddress` is defined in crate `vm_memory`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vm-memory-0.12.2/src/guest_memory.rs:109:1
    |
109 | pub struct GuestAddress(pub u64);
    | ^^^^^^^^^^^^^^^^^^^^^^^
note: `GuestAddress` is defined in crate `vm_memory`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vm-memory-0.13.1/src/guest_memory.rs:111:1
    |
111 | pub struct GuestAddress(pub u64);
    | ^^^^^^^^^^^^^^^^^^^^^^^
    = note: perhaps two different versions of crate `vm_memory` are being used?
note: method defined here
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/virtio-queue-0.9.1/src/queue.rs:132:12
    |
132 |     pub fn try_set_desc_table_address(&mut self, desc_table: GuestAddress) -> Result<(), Error> {
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vhost-user-backend-0.10.1/src/vring.rs:187:41
    |
187 |             .try_set_avail_ring_address(GuestAddress(avail_ring))?;
    |              -------------------------- ^^^^^^^^^^^^^^^^^^^^^^^^ expected `GuestAddress`, found a different `GuestAddress`
    |              |
    |              arguments to this method are incorrect
    |
    = note: `GuestAddress` and `GuestAddress` have similar names, but are actually distinct types
note: `GuestAddress` is defined in crate `vm_memory`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vm-memory-0.12.2/src/guest_memory.rs:109:1
    |
109 | pub struct GuestAddress(pub u64);
    | ^^^^^^^^^^^^^^^^^^^^^^^
note: `GuestAddress` is defined in crate `vm_memory`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vm-memory-0.13.1/src/guest_memory.rs:111:1
    |
111 | pub struct GuestAddress(pub u64);
    | ^^^^^^^^^^^^^^^^^^^^^^^
    = note: perhaps two different versions of crate `vm_memory` are being used?
note: method defined here
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/virtio-queue-0.9.1/src/queue.rs:147:12
    |
147 |     pub fn try_set_avail_ring_address(&mut self, avail_ring: GuestAddress) -> Result<(), Error> {
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vhost-user-backend-0.10.1/src/vring.rs:189:40
    |
189 |             .try_set_used_ring_address(GuestAddress(used_ring))
    |              ------------------------- ^^^^^^^^^^^^^^^^^^^^^^^ expected `GuestAddress`, found a different `GuestAddress`
    |              |
    |              arguments to this method are incorrect
    |
    = note: `GuestAddress` and `GuestAddress` have similar names, but are actually distinct types
note: `GuestAddress` is defined in crate `vm_memory`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vm-memory-0.12.2/src/guest_memory.rs:109:1
    |
109 | pub struct GuestAddress(pub u64);
    | ^^^^^^^^^^^^^^^^^^^^^^^
note: `GuestAddress` is defined in crate `vm_memory`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vm-memory-0.13.1/src/guest_memory.rs:111:1
    |
111 | pub struct GuestAddress(pub u64);
    | ^^^^^^^^^^^^^^^^^^^^^^^
    = note: perhaps two different versions of crate `vm_memory` are being used?
note: method defined here
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/virtio-queue-0.9.1/src/queue.rs:161:12
    |
161 |     pub fn try_set_used_ring_address(&mut self, used_ring: GuestAddress) -> Result<(), Error> {
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0277]: the trait bound `<M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory` is not satisfied
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vhost-user-backend-0.10.1/src/vring.rs:210:23
    |
210 |             .used_idx(self.mem.memory().deref(), Ordering::Relaxed)
    |              -------- ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `vm_memory::guest_memory::GuestMemory` is not implemented for `<M as GuestAddressSpace>::M`
    |              |
    |              required by a bound introduced by this call
    |
note: required by a bound in `used_idx`
   --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/virtio-queue-0.9.1/src/lib.rs:190:20
    |
190 |     fn used_idx<M: GuestMemory>(&self, mem: &M, order: Ordering) -> Result<Wrapping<u16>, Error>;
    |                    ^^^^^^^^^^^ required by this bound in `QueueT::used_idx`
help: consider further restricting the associated type
    |
208 |     fn queue_used_idx(&self) -> Result<u16, VirtQueError> where <M as GuestAddressSpace>::M: vm_memory::guest_memory::GuestMemory {
    |                                                           +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Some errors have detailed explanations: E0277, E0308.
For more information about an error, try `rustc --explain E0277`.
error: could not compile `vhost-user-backend` (lib) due to 8 previous errors

Originally posted by @epilys in rust-vmm/vhost-device#493 (comment)

[Ablu]

While I am not sure what the musl support situation is for pipewire, we have other crates - like vhost-device-gpio, that just do not have musl support. So I would be all for allowing crates to opt out of musl building. In vhost-device-gpio we just #[cfg(...)] the entire main away, but building an empty daemon for musl targets makes little sense to me.

Is there a way to exclude some projects from a workspace depending on the target architecture? That would seem like the simplest way out to me...

[stefano-garzarella]

Is there a way to exclude some projects from a workspace depending on the target architecture? That would seem like the simplest way out to me...

@Ablu It looks like they are still discussing that: rust-lang/cargo#6179

[epilys]

Exclude from CI, at least?

[Ablu]

Exclude from CI, at least?

I would prefer that over doing hacks that just make the daemon build a completely pointless empty binary.

[stefano-garzarella]

Exclude from CI, at least?

I would prefer that over doing hacks that just make the daemon build a completely pointless empty binary.

Yeah, me too. But I'm not sure if we have a way other than writing our own custom pipeline.
@andreeaflorescu ^