diff mbox series

riscv: Set SRCARCH to riscv if ARCH is riscv64 or riscv32

Message ID 479c5c98-0e0d-072d-dae1-f91629989e46@gmail.com (mailing list archive)
State New
Headers show
Series riscv: Set SRCARCH to riscv if ARCH is riscv64 or riscv32 | expand

Commit Message

Ben Westover March 30, 2022, 2:34 p.m. UTC
When riscv64 or riscv32 are used as the value for ARCH during compilation, like
in tools that get the ARCH value from uname, set SRCARCH to riscv instead of
failing because the riscv64 and riscv32 targets don't exist.

Signed-off-by: Ben Westover <kwestover.kw@gmail.com>
---
 Makefile | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Masahiro Yamada March 30, 2022, 3:31 p.m. UTC | #1
On Wed, Mar 30, 2022 at 11:34 PM Ben Westover <kwestover.kw@gmail.com> wrote:
>
> When riscv64 or riscv32 are used as the value for ARCH during compilation, like
> in tools that get the ARCH value from uname, set SRCARCH to riscv instead of
> failing because the riscv64 and riscv32 targets don't exist.

Can you refer to the code that really needs this?




>
> Signed-off-by: Ben Westover <kwestover.kw@gmail.com>
> ---
>  Makefile | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index c28c5d91e5c8..315c364bf2ba 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -408,6 +408,14 @@ ifeq ($(ARCH),parisc64)
>         SRCARCH := parisc
>  endif
>
> +# Additional ARCH settings for riscv
> +ifeq ($(ARCH),riscv32)
> +       SRCARCH := riscv
> +endif
> +ifeq ($(ARCH),riscv64)
> +       SRCARCH := riscv
> +endif
> +
>  export cross_compiling :=
>  ifneq ($(SRCARCH),$(SUBARCH))
>  cross_compiling := 1
> --
> 2.35.1
>
Ben Westover March 30, 2022, 6:40 p.m. UTC | #2
Hello Masahiro,

On 3/30/22 11:31 AM, Masahiro Yamada wrote:
> On Wed, Mar 30, 2022 at 11:34 PM Ben Westover <kwestover.kw@gmail.com> wrote:
>>
>> When riscv64 or riscv32 are used as the value for ARCH during compilation, like
>> in tools that get the ARCH value from uname, set SRCARCH to riscv instead of
>> failing because the riscv64 and riscv32 targets don't exist.
> 
> Can you refer to the code that really needs this?
Some software like DKMS compiles out-of-tree modules by running `uname -m`and
using that for the ARCH value. Without this patch, that compilation fails because
uname shows either riscv64 or riscv32 while riscv should be used.
This code already exists for sparc and parisc, as well as x86 of course.

Thanks,
--
Ben Westover
Masahiro Yamada March 31, 2022, 1:34 a.m. UTC | #3
On Thu, Mar 31, 2022 at 3:40 AM Ben Westover <kwestover.kw@gmail.com> wrote:
>
> Hello Masahiro,
>
> On 3/30/22 11:31 AM, Masahiro Yamada wrote:
> > On Wed, Mar 30, 2022 at 11:34 PM Ben Westover <kwestover.kw@gmail.com> wrote:
> >>
> >> When riscv64 or riscv32 are used as the value for ARCH during compilation, like
> >> in tools that get the ARCH value from uname, set SRCARCH to riscv instead of
> >> failing because the riscv64 and riscv32 targets don't exist.
> >
> > Can you refer to the code that really needs this?
> Some software like DKMS compiles out-of-tree modules by running `uname -m`and
> using that for the ARCH value. Without this patch, that compilation fails because
> uname shows either riscv64 or riscv32 while riscv should be used.

It is a bug in DKMS.

The ARCH=* in linux kernel does not necessarily match to 'uname -m'.

For example, we use ARCH=arm64 for arm 64-bit (so called aarch64),
but it does not match "aarch64".

The kernel has freedom to determine the supported string for ARCH=.

DKMS must adjust to the kernel code.




> This code already exists for sparc and parisc, as well as x86 of course.

This is because there is a historical reason.

If you look at the old code  (e.g. 2.6.x,)
arch/i386/ and arch/x86_64 were separate directories.

They were unified into arch/x86/ now, but we still support
ARCH=i386/x86_64.  It helps to choose a different defconfig.
See arch/x86/Makefile.


I do not see such code for riscv, where 32/64-bit is selected
only by Kconfig.




>
> Thanks,
> --
> Ben Westover
Ben Westover March 31, 2022, 2:16 a.m. UTC | #4
Hello Masahiro,

On 3/30/22 9:34 PM, Masahiro Yamada wrote:
> On Thu, Mar 31, 2022 at 3:40 AM Ben Westover <kwestover.kw@gmail.com> wrote:
>>
>> Hello Masahiro,
>>
>> On 3/30/22 11:31 AM, Masahiro Yamada wrote:
>>> On Wed, Mar 30, 2022 at 11:34 PM Ben Westover <kwestover.kw@gmail.com> wrote:
>>>>
>>>> When riscv64 or riscv32 are used as the value for ARCH during compilation, like
>>>> in tools that get the ARCH value from uname, set SRCARCH to riscv instead of
>>>> failing because the riscv64 and riscv32 targets don't exist.
>>>
>>> Can you refer to the code that really needs this?
>> Some software like DKMS compiles out-of-tree modules by running `uname -m`and
>> using that for the ARCH value. Without this patch, that compilation fails because
>> uname shows either riscv64 or riscv32 while riscv should be used.
> 
> It is a bug in DKMS.
> 
> The ARCH=* in linux kernel does not necessarily match to 'uname -m'.
> 
> For example, we use ARCH=arm64 for arm 64-bit (so called aarch64),
> but it does not match "aarch64".
> 
> The kernel has freedom to determine the supported string for ARCH=.
> 
> DKMS must adjust to the kernel code.

Ah, I see. Originally, I opened an issue in DKMS, but they led me to believe it was
a kernel issue. Now I see that *they* are the ones that need to change.

>> This code already exists for sparc and parisc, as well as x86 of course.
> 
> This is because there is a historical reason.
> 
> If you look at the old code  (e.g. 2.6.x,)
> arch/i386/ and arch/x86_64 were separate directories.
> 
> They were unified into arch/x86/ now, but we still support
> ARCH=i386/x86_64.  It helps to choose a different defconfig.
> See arch/x86/Makefile.

This makes more sense now. DKMS based their ARCH value off of uname, and because of
this vestigial code, it worked on x86. Now, trouble is being run into on other
architectures, and their bad design comes back to haunt them.

Thank you for the info; I will now try to solve these issues in DKMS and open a pull
request since they don't seem want to do it themselves.

Regards,
--
Ben Westover
diff mbox series

Patch

diff --git a/Makefile b/Makefile
index c28c5d91e5c8..315c364bf2ba 100644
--- a/Makefile
+++ b/Makefile
@@ -408,6 +408,14 @@  ifeq ($(ARCH),parisc64)
        SRCARCH := parisc
 endif

+# Additional ARCH settings for riscv
+ifeq ($(ARCH),riscv32)
+       SRCARCH := riscv
+endif
+ifeq ($(ARCH),riscv64)
+       SRCARCH := riscv
+endif
+
 export cross_compiling :=
 ifneq ($(SRCARCH),$(SUBARCH))
 cross_compiling := 1