This is a somewhat blind (and maybe foolish) attempt at enabling Rust
for RISC-V. I've tested this on Icicle, and the modules seem to work.
I'd like to play around with Rust on RISC-V, but I'm not interested in
using downstream kernels, so figured I should try and see what's
missing...
I've tagged this as RFC in case I've missed some "WAaaaa you can't do
this" somewhere :)
Thanks,
Conor.
Changes in RFC-RESEND:
- fixed the asymmetrical additions in the Makefile bits
- added cc-cover to my git send-email command...
CC: Miguel Ojeda <[email protected]>
CC: Alex Gaynor <[email protected]>
CC: Wedson Almeida Filho <[email protected]>
CC: Boqun Feng <[email protected]>
CC: Gary Guo <[email protected]>
CC: Björn Roy Baron <[email protected]>
CC: Jonathan Corbet <[email protected]>
CC: Paul Walmsley <[email protected]>
CC: Palmer Dabbelt <[email protected]>
CC: Nathan Chancellor <[email protected]>
CC: Nick Desaulniers <[email protected]>
CC: Tom Rix <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
Miguel Ojeda (2):
scripts: generate_rust_target: enable building on RISC-V
RISC-V: enable building the 64-bit kernels with rust support
Documentation/rust/arch-support.rst | 2 ++
arch/riscv/Kconfig | 1 +
arch/riscv/Makefile | 3 ++-
scripts/generate_rust_target.rs | 19 +++++++++++++++++++
4 files changed, 24 insertions(+), 1 deletion(-)
--
2.39.2
From: Miguel Ojeda <[email protected]>
Add the required bits from rust-for-linux to enable generating a RISC-V
target for rust.
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Conor Dooley <[email protected]>
---
scripts/generate_rust_target.rs | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 3c6cbe2b278d..72428fc66502 100644
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -161,6 +161,25 @@ fn main() {
ts.push("features", features);
ts.push("llvm-target", "x86_64-linux-gnu");
ts.push("target-pointer-width", "64");
+ } else if cfg.has("RISCV") {
+ if cfg.has("64BIT") {
+ ts.push("arch", "riscv64");
+ ts.push("data-layout", "e-m:e-p:64:64-i64:64-i128:128-n64-S128");
+ ts.push("llvm-target", "riscv64-linux-gnu");
+ ts.push("target-pointer-width", "64");
+ } else {
+ ts.push("arch", "riscv32");
+ ts.push("data-layout", "e-m:e-p:32:32-i64:64-n32-S128");
+ ts.push("llvm-target", "riscv32-linux-gnu");
+ ts.push("target-pointer-width", "32");
+ }
+ ts.push("code-model", "medium");
+ ts.push("disable-redzone", true);
+ let mut features = "+m,+a".to_string();
+ if cfg.has("RISCV_ISA_C") {
+ features += ",+c";
+ }
+ ts.push("features", features);
} else {
panic!("Unsupported architecture");
}
--
2.39.2
From: Miguel Ojeda <[email protected]>
The rust modules work on 64-bit RISC-V, with no twiddling required.
Select HAS_RUST and provide the required flags to kbuild so that the
modules can be used.
32-bit is broken in core rust code, so support is limited to 64-bit
only: ld.lld: error: undefined symbol: __udivdi3
Signed-off-by: Miguel Ojeda <[email protected]>
Signed-off-by: Conor Dooley <[email protected]>
---
Documentation/rust/arch-support.rst | 2 ++
arch/riscv/Kconfig | 1 +
arch/riscv/Makefile | 3 ++-
3 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
index 6982b63775da..197919158596 100644
--- a/Documentation/rust/arch-support.rst
+++ b/Documentation/rust/arch-support.rst
@@ -15,5 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
============ ================ ==============================================
Architecture Level of support Constraints
============ ================ ==============================================
+``riscv`` Maintained ``rv64`` only.
+============ ================ ==============================================
``x86`` Maintained ``x86_64`` only.
============ ================ ==============================================
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 81eb031887d2..73174157212d 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -115,6 +115,7 @@ config RISCV
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RSEQ
+ select HAVE_RUST if 64BIT
select HAVE_STACKPROTECTOR
select HAVE_SYSCALL_TRACEPOINTS
select IRQ_DOMAIN
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 76989561566b..0d6fc4e25221 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -29,8 +29,8 @@ ifeq ($(CONFIG_ARCH_RV64I),y)
KBUILD_CFLAGS += -mabi=lp64
KBUILD_AFLAGS += -mabi=lp64
-
KBUILD_LDFLAGS += -melf64lriscv
+ KBUILD_RUSTFLAGS += -Ctarget-cpu=generic-rv64
else
BITS := 32
UTS_MACHINE := riscv32
@@ -38,6 +38,7 @@ else
KBUILD_CFLAGS += -mabi=ilp32
KBUILD_AFLAGS += -mabi=ilp32
KBUILD_LDFLAGS += -melf32lriscv
+ KBUILD_RUSTFLAGS += -Ctarget-cpu=generic-rv32
endif
ifeq ($(CONFIG_LD_IS_LLD),y)
--
2.39.2
Hi Conor,
On Fri, Feb 24, 2023 at 01:50:44PM +0000, Conor Dooley wrote:
> From: Miguel Ojeda <[email protected]>
>
> The rust modules work on 64-bit RISC-V, with no twiddling required.
> Select HAS_RUST and provide the required flags to kbuild so that the
> modules can be used.
> 32-bit is broken in core rust code, so support is limited to 64-bit
> only: ld.lld: error: undefined symbol: __udivdi3
>
> Signed-off-by: Miguel Ojeda <[email protected]>
> Signed-off-by: Conor Dooley <[email protected]>
> ---
> Documentation/rust/arch-support.rst | 2 ++
> arch/riscv/Kconfig | 1 +
> arch/riscv/Makefile | 3 ++-
> 3 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
> index 6982b63775da..197919158596 100644
> --- a/Documentation/rust/arch-support.rst
> +++ b/Documentation/rust/arch-support.rst
> @@ -15,5 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
> ============ ================ ==============================================
> Architecture Level of support Constraints
> ============ ================ ==============================================
> +``riscv`` Maintained ``rv64`` only.
> +============ ================ ==============================================
> ``x86`` Maintained ``x86_64`` only.
> ============ ================ ==============================================
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 81eb031887d2..73174157212d 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -115,6 +115,7 @@ config RISCV
> select HAVE_POSIX_CPU_TIMERS_TASK_WORK
> select HAVE_REGS_AND_STACK_ACCESS_API
> select HAVE_RSEQ
> + select HAVE_RUST if 64BIT
Just a small drive by comment, you have 'if 64BIT' here...
> select HAVE_STACKPROTECTOR
> select HAVE_SYSCALL_TRACEPOINTS
> select IRQ_DOMAIN
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 76989561566b..0d6fc4e25221 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -29,8 +29,8 @@ ifeq ($(CONFIG_ARCH_RV64I),y)
>
> KBUILD_CFLAGS += -mabi=lp64
> KBUILD_AFLAGS += -mabi=lp64
> -
> KBUILD_LDFLAGS += -melf64lriscv
> + KBUILD_RUSTFLAGS += -Ctarget-cpu=generic-rv64
> else
> BITS := 32
> UTS_MACHINE := riscv32
> @@ -38,6 +38,7 @@ else
> KBUILD_CFLAGS += -mabi=ilp32
> KBUILD_AFLAGS += -mabi=ilp32
> KBUILD_LDFLAGS += -melf32lriscv
> + KBUILD_RUSTFLAGS += -Ctarget-cpu=generic-rv32
but also add KBUILD_RUSTFLAGS for the !64BIT case. Seems like one of
those can be removed.
> endif
>
> ifeq ($(CONFIG_LD_IS_LLD),y)
> --
> 2.39.2
>
Cheers,
Nathan
On Fri, Feb 24, 2023 at 07:57:13AM -0700, Nathan Chancellor wrote:
> Hi Conor,
>
> On Fri, Feb 24, 2023 at 01:50:44PM +0000, Conor Dooley wrote:
> > From: Miguel Ojeda <[email protected]>
> >
> > The rust modules work on 64-bit RISC-V, with no twiddling required.
> > Select HAS_RUST and provide the required flags to kbuild so that the
> > modules can be used.
> > 32-bit is broken in core rust code, so support is limited to 64-bit
> > only: ld.lld: error: undefined symbol: __udivdi3
> >
> > Signed-off-by: Miguel Ojeda <[email protected]>
> > Signed-off-by: Conor Dooley <[email protected]>
> > ---
> > Documentation/rust/arch-support.rst | 2 ++
> > arch/riscv/Kconfig | 1 +
> > arch/riscv/Makefile | 3 ++-
> > 3 files changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
> > index 6982b63775da..197919158596 100644
> > --- a/Documentation/rust/arch-support.rst
> > +++ b/Documentation/rust/arch-support.rst
> > @@ -15,5 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
> > ============ ================ ==============================================
> > Architecture Level of support Constraints
> > ============ ================ ==============================================
> > +``riscv`` Maintained ``rv64`` only.
> > +============ ================ ==============================================
> > ``x86`` Maintained ``x86_64`` only.
> > ============ ================ ==============================================
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 81eb031887d2..73174157212d 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -115,6 +115,7 @@ config RISCV
> > select HAVE_POSIX_CPU_TIMERS_TASK_WORK
> > select HAVE_REGS_AND_STACK_ACCESS_API
> > select HAVE_RSEQ
> > + select HAVE_RUST if 64BIT
>
> Just a small drive by comment, you have 'if 64BIT' here...
>
> > select HAVE_STACKPROTECTOR
> > select HAVE_SYSCALL_TRACEPOINTS
> > select IRQ_DOMAIN
> > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> > index 76989561566b..0d6fc4e25221 100644
> > --- a/arch/riscv/Makefile
> > +++ b/arch/riscv/Makefile
> > @@ -29,8 +29,8 @@ ifeq ($(CONFIG_ARCH_RV64I),y)
> >
> > KBUILD_CFLAGS += -mabi=lp64
> > KBUILD_AFLAGS += -mabi=lp64
> > -
> > KBUILD_LDFLAGS += -melf64lriscv
> > + KBUILD_RUSTFLAGS += -Ctarget-cpu=generic-rv64
> > else
> > BITS := 32
> > UTS_MACHINE := riscv32
> > @@ -38,6 +38,7 @@ else
> > KBUILD_CFLAGS += -mabi=ilp32
> > KBUILD_AFLAGS += -mabi=ilp32
> > KBUILD_LDFLAGS += -melf32lriscv
> > + KBUILD_RUSTFLAGS += -Ctarget-cpu=generic-rv32
>
> but also add KBUILD_RUSTFLAGS for the !64BIT case. Seems like one of
> those can be removed.
Yeah & it's ditto for the rv32 handling in 1/2 as well. Ideally there
wouldn't be implicit 64-bit division and the "if 64BIT" could go
away. I just left things as-lifted, but I'll go drop anything 32-bit
related if this series looses the RFC prefix ;)
On Fri, Feb 24, 2023 at 2:51 PM Conor Dooley <[email protected]> wrote:
>
> The rust modules work on 64-bit RISC-V, with no twiddling required.
> Select HAS_RUST and provide the required flags to kbuild so that the
HAS -> HAVE
> diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
> index 6982b63775da..197919158596 100644
> --- a/Documentation/rust/arch-support.rst
> +++ b/Documentation/rust/arch-support.rst
> @@ -15,5 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
> ============ ================ ==============================================
> Architecture Level of support Constraints
> ============ ================ ==============================================
> +``riscv`` Maintained ``rv64`` only.
> +============ ================ ==============================================
> ``x86`` Maintained ``x86_64`` only.
I think this separator between rows should not be here (it is not in
`rust-for-linux/rust`). Please see
https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#simple-tables.
Cheers,
Miguel
On Fri, Feb 24, 2023 at 09:45:05PM +0100, Miguel Ojeda wrote:
> On Fri, Feb 24, 2023 at 2:51 PM Conor Dooley <[email protected]> wrote:
> > diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
> > index 6982b63775da..197919158596 100644
> > --- a/Documentation/rust/arch-support.rst
> > +++ b/Documentation/rust/arch-support.rst
> > @@ -15,5 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
> > ============ ================ ==============================================
> > Architecture Level of support Constraints
> > ============ ================ ==============================================
> > +``riscv`` Maintained ``rv64`` only.
> > +============ ================ ==============================================
> > ``x86`` Maintained ``x86_64`` only.
>
> I think this separator between rows should not be here (it is not in
> `rust-for-linux/rust`). Please see
> https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#simple-tables.
That's what the "let the automation tell me if I messed up rst" approach
gets you ;)