rust: Modify Rust to be usable as host-tool only

Message ID 20180717042953.23648-1-sam.voss@gmail.com
State New
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Series
  • rust: Modify Rust to be usable as host-tool only
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Commit Message

Samuel Voss July 17, 2018, 4:29 a.m.
From: Sam Voss <sam.voss@gmail.com>

Modify host-rust virtual package to default to host-rust-bin when no
other selection has been made, as long as the host supports rust. This
allows host only tools to still use rust when the target architecture
does not support it.

Add target-specific variable which is used to differentiate host and
target arch requirements (BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS).

A target package shall depend on this variable where a host package will
use the previously defined BR2_PACKAGE_HOST_RUSTC_ARCH_SUPPORTS. The new
"target" version is selectable for the same set of architectures as
before, but now depends on the host variant.

Signed-off-by: Sam Voss <sam.voss@gmail.com>
---

Note: this has been tested on x86_64 host compiling to:

- x86_64 qemu target (building package to be upstreamed shortly)
- mips64el (based on librsvg build failures seen at
http://autobuild.buildroot.net/results/f33/f335ed517b402c094ed3b10a3da4cdc23620dbd6/defconfig)
  this target was only tested to compile, with no runtime tests.

 package/rust-bin/rust-bin.mk |  5 ++++-
 package/rust/rust.mk         |  1 +
 package/rustc/Config.in.host | 21 ++++++++++++++++++---
 package/rustc/rustc.mk       |  2 ++
 4 files changed, 25 insertions(+), 4 deletions(-)

Comments

Eric Le Bihan July 17, 2018, 11:18 a.m. | #1
Hi!

> From: Sam Voss <sam.voss@gmail.com>
> 
> Modify host-rust virtual package to default to host-rust-bin when no
> other selection has been made, as long as the host supports rust. This
> allows host only tools to still use rust when the target architecture
> does not support it.
> 
> Add target-specific variable which is used to differentiate host and
> target arch requirements (BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS).
> 
> A target package shall depend on this variable where a host package will 
> use the previously defined BR2_PACKAGE_HOST_RUSTC_ARCH_SUPPORTS. The new 
> "target" version is selectable for the same set of architectures as
> before, but now depends on the host variant.
> 
> Signed-off-by: Sam Voss <sam.voss@gmail.com>

IIUC, the goal of this patch is to be able to build host packages which need 
rust, so host-rust-bin is set as default to avoid errors on empty variables
and only the compiler and the host standard library are installed (not the
target standard library). Only x86_64/x86 support is required, right?

I find it confusing that BR2_PACKAGE_HOST_RUSTC_ARCH_SUPPORTS and 
BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS are quite similar and that in 
the end BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS is only used to install
the target standard library. Is that meant to cover the case where the host
and the target are the same (x86_64) or the librsvg-related issue?

Would this be solved by introducing a virtual package for the target 
standard library as previously discussed [1]?

[1] http://patchwork.ozlabs.org/comment/1830134/ 

Regards,

--
ELB
Samuel Voss July 17, 2018, 5:34 p.m. | #2
Eric,

On Tue, Jul 17, 2018 at 6:18 AM, Eric Le Bihan
<eric.le.bihan.dev@free.fr> wrote:
> Hi!
>
>> From: Sam Voss <sam.voss@gmail.com>
>>
>> Modify host-rust virtual package to default to host-rust-bin when no
>> other selection has been made, as long as the host supports rust. This
>> allows host only tools to still use rust when the target architecture
>> does not support it.
>>
>> Add target-specific variable which is used to differentiate host and
>> target arch requirements (BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS).
>>
>> A target package shall depend on this variable where a host package will
>> use the previously defined BR2_PACKAGE_HOST_RUSTC_ARCH_SUPPORTS. The new
>> "target" version is selectable for the same set of architectures as
>> before, but now depends on the host variant.
>>
>> Signed-off-by: Sam Voss <sam.voss@gmail.com>
>
> IIUC, the goal of this patch is to be able to build host packages which need
> rust, so host-rust-bin is set as default to avoid errors on empty variables
> and only the compiler and the host standard library are installed (not the
> target standard library). Only x86_64/x86 support is required, right?

That is correct. This boils down to being able to build a host tool on
supported platforms when the target isn't.

>
> I find it confusing that BR2_PACKAGE_HOST_RUSTC_ARCH_SUPPORTS and
> BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS are quite similar and that in
> the end BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS is only used to install
> the target standard library. Is that meant to cover the case where the host
> and the target are the same (x86_64) or the librsvg-related issue?

The target was the librsvg build issues, I'm not sure it does anything
special for the target-same builds as it'll just fall into the same
scenario as the previous itteration (nothing will be gated off).

>
> Would this be solved by introducing a virtual package for the target
> standard library as previously discussed [1]?

I actually missed this conversation, and on paper I like the virtual
package but I think it is a lot more work (which is OK, but it might
be worth iterating to that point).

Thanks,

Sam

Patch

diff --git a/package/rust-bin/rust-bin.mk b/package/rust-bin/rust-bin.mk
index e10dbcebd0..c426da8d15 100644
--- a/package/rust-bin/rust-bin.mk
+++ b/package/rust-bin/rust-bin.mk
@@ -15,7 +15,10 @@  HOST_RUST_BIN_SOURCE = rustc-$(RUST_BIN_VERSION)-$(RUSTC_HOST_NAME).tar.xz
 
 HOST_RUST_BIN_EXTRA_DOWNLOADS = \
 	rust-std-$(RUST_BIN_VERSION)-$(RUSTC_HOST_NAME).tar.xz \
-	rust-std-$(RUST_BIN_VERSION)-$(RUSTC_TARGET_NAME).tar.xz
+
+ifeq ($(BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS),y)
+HOST_RUST_BIN_EXTRA_DOWNLOADS += rust-std-$(RUST_BIN_VERSION)-$(RUSTC_TARGET_NAME).tar.xz
+endif
 
 HOST_RUST_BIN_LIBSTD_HOST_PREFIX = rust-std-$(RUST_BIN_VERSION)-$(RUSTC_HOST_NAME)/rust-std-$(RUSTC_HOST_NAME)
 
diff --git a/package/rust/rust.mk b/package/rust/rust.mk
index af5c366495..c11dbb23b0 100644
--- a/package/rust/rust.mk
+++ b/package/rust/rust.mk
@@ -19,6 +19,7 @@  HOST_RUST_DEPENDENCIES = \
 	host-python \
 	$(BR2_CMAKE_HOST_DEPENDENCY)
 
+
 ifeq ($(BR2_PACKAGE_JEMALLOC),y)
 HOST_RUST_DEPENDENCIES += jemalloc
 HOST_RUST_JEMALLOC_ENABLED = true
diff --git a/package/rustc/Config.in.host b/package/rustc/Config.in.host
index 2ae8f89d3f..d7f0efcd3f 100644
--- a/package/rustc/Config.in.host
+++ b/package/rustc/Config.in.host
@@ -14,6 +14,19 @@  config BR2_PACKAGE_HOST_RUSTC_ARCH_SUPPORTS
 	depends on BR2_TOOLCHAIN_USES_GLIBC
 	depends on BR2_HOSTARCH = "x86_64" || BR2_HOSTARCH = "x86"
 
+config BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS
+	bool
+	default y if BR2_i386
+	default y if BR2_x86_64
+	default y if BR2_aarch64
+	default y if BR2_arm && !BR2_ARM_CPU_ARMV4 && !BR2_ARM_CPU_ARMV5 \
+	        && !(BR2_ARM_CPU_ARMV7A && BR2_ARM_EABI)
+	default y if BR2_powerpc || BR2_powerpc64 || BR2_powerpc64le
+	default y if (BR2_mips || BR2_mipsel) && !BR2_MIPS_CPU_MIPS32R6
+	default y if (BR2_mips64 || BR2_mips64el) && !BR2_MIPS_CPU_MIPS64R6 \
+		&& BR2_MIPS_NABI64
+	depends on BR2_PACKAGE_HOST_RUSTC_ARCH_SUPPORTS
+
 config BR2_PACKAGE_HOST_RUSTC_ARCH
 	string
 	default "armv7"  if BR2_ARM_CPU_ARMV7A
@@ -66,9 +79,11 @@  config BR2_PACKAGE_HOST_RUST_BIN
 
 endchoice
 
+endif
+
 config BR2_PACKAGE_PROVIDES_HOST_RUSTC
 	string
 	default "host-rust" if BR2_PACKAGE_HOST_RUST
-	default "host-rust-bin" if BR2_PACKAGE_HOST_RUST_BIN
-
-endif
+	# Default to host-rust-bin as long as host arch supports it
+	default "host-rust-bin" if !BR2_PACKAGE_HOST_RUST
+	depends on BR2_PACKAGE_HOST_RUSTC_ARCH_SUPPORTS
diff --git a/package/rustc/rustc.mk b/package/rustc/rustc.mk
index bed74f3c2c..6eea9b4fc5 100644
--- a/package/rustc/rustc.mk
+++ b/package/rustc/rustc.mk
@@ -7,7 +7,9 @@ 
 RUSTC_ARCH = $(call qstrip,$(BR2_PACKAGE_HOST_RUSTC_ARCH))
 RUSTC_ABI = $(call qstrip,$(BR2_PACKAGE_HOST_RUSTC_ABI))
 
+ifeq ($(BR2_PACKAGE_HOST_RUSTC_TARGET_ARCH_SUPPORTS),y)
 RUSTC_TARGET_NAME = $(RUSTC_ARCH)-unknown-linux-gnu$(RUSTC_ABI)
+endif
 
 ifeq ($(HOSTARCH),x86)
 RUSTC_HOST_ARCH = i686