Can CT-NG build a RISC-V picolibc toolchain?

Can CT-NG build a RISC-V picolibc toolchain?

[Tommy Murphy]

Hi there

Apologies in advance if this is a dumb question or one that has been answered already but I tried searching but couldn't find anything on it...

Can I use CT-NG to build a RISC-V bare metal toolchain that uses picolibc as the standard library? Can I build one that bundles newlib, newlib-nano and picolibc which can be switched between using the relevant specs files as can be done for Arm?

If so, what configuration settings do I need? I can't see a way to do this using the menuconfig. If it's possible, does it perhaps need a manually edited config file?

I've been playing with the latest CT-NG cloned from the master branch in github. I've enabled the experimental option in order to be able to build a RISC-V newlib toolchain which works fine. But I can't see a way to build a picolibc one or a newlib/newlib-nano/picolibc one. I've also used one of the sample configurations to build an Arm multilib toolchain that bundles newlib/newlib-nano/picolibc.

Thanks a lot for any guidance/advice.

Can CT-NG build a RISC-V picolibc toolchain?

[Tommy Murphy]

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Hi there

Apologies in advance if this is a dumb question or one that has been answered already but I tried searching but couldn't find anything on it...

Can I use CT-NG to build a RISC-V bare metal toolchain that uses picolibc as the standard library? Can I build one that bundles newlib, newlib-nano and picolibc which can be switched between using the relevant specs files as can be done for Arm?

If so, what configuration settings do I need? I can't see a way to do this using the menuconfig. If it's possible, does it perhaps need a manually edited config file?

I've been playing with the latest CT-NG cloned from the master branch in github. I've enabled the experimental option in order to be able to build a RISC-V newlib toolchain which works fine. But I can't see a way to build a picolibc one or a newlib/newlib-nano/picolibc one. I've also used one of the sample configurations to build an Arm multilib toolchain that bundles newlib/newlib-nano/picolibc.

Thanks a lot for any guidance/advice.

Re: Can CT-NG build a RISC-V picolibc toolchain?

[Keith Packard]

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Tommy Murphy via crossgcc <crossgcc@sourceware.org> writes:

> Can I use CT-NG to build a RISC-V bare metal toolchain that uses
> picolibc as the standard library? Can I build one that bundles newlib,
> newlib-nano and picolibc which can be switched between using the
> relevant specs files as can be done for Arm?

Yup. The "trick" is that newlib-nano and picolibc are 'companion'
libraries, so you won't find them in the obvious place in the
menus. That was the easy way to integrate all three C libraries into the
existing ct-ng code.

I just tried building a riscv toolchain with ct-ng master and it worked
fine. I started with riscv32-unknown-elf, added multilib, newlib-nano
and picolibc. I did have to explicitly disable default-pie.

-- 
-keith

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Re: Can CT-NG build a RISC-V picolibc toolchain?

[Tommy Murphy]

Hi Keith

Thanks a lot. I'll try again tomorrow and see how it goes and post back if necessary.

Thanks again

Re: Can CT-NG build a RISC-V picolibc toolchain?

[Tommy Murphy]

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Hi Keith

Thanks a lot. I'll try again tomorrow and see how it goes and post back if necessary.

Thanks again

Re: Can CT-NG build a RISC-V picolibc toolchain?

[Keith Packard]

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Tommy Murphy <tommy_murphy@hotmail.com> writes:

> Hi Keith
>
> So, my (non multilib for now) build of the RISC-V tools with newlib,
> newlib-nano and picolibc succeeded. I also had to disable the PIC
> option. With it enabled the picolibc build failed with an error about
> not being able to find the dynamic linker (sorry, forgot to save the
> verbatim error). Do you have the idea why that happens? I guess that
> PIC is largely, or maybe totally, irrelevant for a bare metal
> toolchain with no shared lib requirements?

Yup, you don't need pic as you won't have a dynamic linker.

> Thanks again for your help in making progress on this.

Glad you got it working.

-- 
-keith

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Re: Can CT-NG build a RISC-V picolibc toolchain?

[Tommy Murphy]

Hi Keith

So, my (non multilib for now) build of the RISC-V tools with newlib, newlib-nano and picolibc succeeded. I also had to disable the PIC option. With it enabled the picolibc build failed with an error about not being able to find the dynamic linker (sorry, forgot to save the verbatim error). Do you have the idea why that happens? I guess that PIC is largely, or maybe totally, irrelevant for a bare metal toolchain with no shared lib requirements?

Thanks again for your help in making progress on this.
________________________________
From: Tommy Murphy <tommy_murphy@hotmail.com>
Sent: Saturday, August 27, 2022 3:22:42 PM
To: Keith Packard <keithp@keithp.com>; crossgcc@sourceware.org <crossgcc@sourceware.org>
Subject: Re: Can CT-NG build a RISC-V picolibc toolchain?

Ok - maybe it was a bit of a dumb question!
I completely overlooked the fact that the Companion Libraries section of menuconfig has options for newlib-nano and picolibc.
I was fixated on the C Library section so missed these.
I'm trying a new build now with these enabled (newlib, newlib-nano and picolibc).
Thanks again for the assistance.

Re: Can CT-NG build a RISC-V picolibc toolchain?

[Tommy Murphy]

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Hi Keith

So, my (non multilib for now) build of the RISC-V tools with newlib, newlib-nano and picolibc succeeded. I also had to disable the PIC option. With it enabled the picolibc build failed with an error about not being able to find the dynamic linker (sorry, forgot to save the verbatim error). Do you have the idea why that happens? I guess that PIC is largely, or maybe totally, irrelevant for a bare metal toolchain with no shared lib requirements?

Thanks again for your help in making progress on this.
________________________________
From: Tommy Murphy <tommy_murphy@hotmail.com>
Sent: Saturday, August 27, 2022 3:22:42 PM
To: Keith Packard <keithp@keithp.com>; crossgcc@sourceware.org <crossgcc@sourceware.org>
Subject: Re: Can CT-NG build a RISC-V picolibc toolchain?

Ok - maybe it was a bit of a dumb question!
I completely overlooked the fact that the Companion Libraries section of menuconfig has options for newlib-nano and picolibc.
I was fixated on the C Library section so missed these.
I'm trying a new build now with these enabled (newlib, newlib-nano and picolibc).
Thanks again for the assistance.

Re: Can CT-NG build a RISC-V picolibc toolchain?

[Tommy Murphy]

Ok - maybe it was a bit of a dumb question!
I completely overlooked the fact that the Companion Libraries section of menuconfig has options for newlib-nano and picolibc.
I was fixated on the C Library section so missed these.
I'm trying a new build now with these enabled (newlib, newlib-nano and picolibc).
Thanks again for the assistance.

Re: Can CT-NG build a RISC-V picolibc toolchain?

[Tommy Murphy]

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Ok - maybe it was a bit of a dumb question!
I completely overlooked the fact that the Companion Libraries section of menuconfig has options for newlib-nano and picolibc.
I was fixated on the C Library section so missed these.
I'm trying a new build now with these enabled (newlib, newlib-nano and picolibc).
Thanks again for the assistance.