[gentoo-dev] Announcing RISC-V

[gentoo-dev] Announcing RISC-V

[Andreas K. Huettel]

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Hi all, 

after some preparations, we're happy to announce (initially experimental) 
support for a new arch: riscv

* The project page is at https://wiki.gentoo.org/wiki/Project:RISC-V
  Feel free to join if you want to help and/or even have hardware.
  We also have a dedicated IRC channel, #gentoo-riscv

* The keyword is "~riscv"; no stable keyword will be used in the beginning.

* We will initially add two profiles to profile.desc: 
  default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit hardfloat)
  default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, i.e. hard/softfloat)

* Stage builds have been tested with an overlay and work fine.
  I'll publish initial stage3 images soon and will work with releng to get
  autobuilds running.

* Once this all is done I'll draft an announcement for the main web page.

Cheers, 
Andreas

-- 
Andreas K. Hüttel
dilfridge@gentoo.org
Gentoo Linux developer
(council, toolchain, base-system, perl, libreoffice)

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[gentoo-dev] Re: Announcing RISC-V

[Sergei Trofimovich]

On Fri, 03 May 2019 23:34:40 +0200
"Andreas K. Huettel" <dilfridge@gentoo.org> wrote:

> Hi all, 
> 
> after some preparations, we're happy to announce (initially experimental) 
> support for a new arch: riscv
> 
> * The project page is at https://wiki.gentoo.org/wiki/Project:RISC-V
>   Feel free to join if you want to help and/or even have hardware.
>   We also have a dedicated IRC channel, #gentoo-riscv
> 
> * The keyword is "~riscv"; no stable keyword will be used in the beginning.
> 
> * We will initially add two profiles to profile.desc: 
>   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit hardfloat)
>   default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, i.e. hard/softfloat)

Please fill out https://wiki.gentoo.org/wiki/RISC-V_Multilib
It's absolutely unclear what LIBDIR is supposed to be in multilib/non-multilib
case without looking at profiles.

> * Stage builds have been tested with an overlay and work fine.
>   I'll publish initial stage3 images soon and will work with releng to get
>   autobuilds running.
> 
> * Once this all is done I'll draft an announcement for the main web page.

-- 

  Sergei

Re: [gentoo-dev] Announcing RISC-V

[Tobias Klausmann]

Hi! 

On Fri, 03 May 2019, Andreas K. Huettel wrote:
> after some preparations, we're happy to announce (initially experimental) 
> support for a new arch: riscv
> 
> * The project page is at https://wiki.gentoo.org/wiki/Project:RISC-V
>   Feel free to join if you want to help and/or even have hardware.
>   We also have a dedicated IRC channel, #gentoo-riscv
> 
> * The keyword is "~riscv"; no stable keyword will be used in the beginning.
> 
> * We will initially add two profiles to profile.desc: 
>   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit hardfloat)
>   default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, i.e. hard/softfloat)
> 
> * Stage builds have been tested with an overlay and work fine.
>   I'll publish initial stage3 images soon and will work with releng to get
>   autobuilds running.
> 
> * Once this all is done I'll draft an announcement for the main web page.

I'm a sucker for exotic arches. What is the recommended hardware
to use to be able help with testing?

Best,
Tobias

-- 
printk ("Barf\n");
        linux-2.6.6/arch/v850/kernel/module.c

Re: [gentoo-dev] Announcing RISC-V

[Pengcheng Xu]

Hi!

2019年5月5日(日) 0:32 Tobias Klausmann <klausman@gentoo.org>:
>
> Hi!
>
> On Fri, 03 May 2019, Andreas K. Huettel wrote:
> > after some preparations, we're happy to announce (initially experimental)
> > support for a new arch: riscv
> >
> > * The project page is at https://wiki.gentoo.org/wiki/Project:RISC-V
> >   Feel free to join if you want to help and/or even have hardware.
> >   We also have a dedicated IRC channel, #gentoo-riscv
> >
> > * The keyword is "~riscv"; no stable keyword will be used in the beginning.
> >
> > * We will initially add two profiles to profile.desc:
> >   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit hardfloat)
> >   default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, i.e. hard/softfloat)
> >
> > * Stage builds have been tested with an overlay and work fine.
> >   I'll publish initial stage3 images soon and will work with releng to get
> >   autobuilds running.
> >
> > * Once this all is done I'll draft an announcement for the main web page.
>
> I'm a sucker for exotic arches. What is the recommended hardware
> to use to be able help with testing?

SiFive's "Hifive Unleashed" seems to be the best RISC-V dev-board
available: quad-core at 1.5GHz with 8GB RAM in 28nm.  Link:
https://www.sifive.com/boards/hifive-unleashed

Currently working on the board with jiegec at #gentoo-riscv.

>
> Best,
> Tobias
>
> --
> printk ("Barf\n");
>         linux-2.6.6/arch/v850/kernel/module.c
>

Yours,
-- 
Pengcheng

[gentoo-dev] Re: Announcing RISC-V

[Andreas K. Huettel]

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So here's a small update:

* An initial stage is available at 
  https://dev.gentoo.org/~dilfridge/stages/rv64gc-multilib/
  It's verified working, in the sense that I can unpack it, chroot
  into it, and have it rebuild itself (emerge -eav world) without errors.

* @system is keyworded, and the multilib profile has been marked stable
  (i.e. repoman will enforce dependency-tree consistency).
  A lot of useflags are still masked though. Also, *only* python-3.7 is
  available.

Cheers, 
Andreas

Am Freitag, 3. Mai 2019, 23:34:40 CEST schrieb Andreas K. Huettel:
> Hi all,
> 
> after some preparations, we're happy to announce (initially experimental)
> support for a new arch: riscv
> 
> * The project page is at https://wiki.gentoo.org/wiki/Project:RISC-V
>   Feel free to join if you want to help and/or even have hardware.
>   We also have a dedicated IRC channel, #gentoo-riscv
> 
> * The keyword is "~riscv"; no stable keyword will be used in the beginning.
> 
> * We will initially add two profiles to profile.desc:
>   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit hardfloat)
>   default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, i.e. hard/softfloat)
> 
> * Stage builds have been tested with an overlay and work fine.
>   I'll publish initial stage3 images soon and will work with releng to get
>   autobuilds running.
> 
> * Once this all is done I'll draft an announcement for the main web page.
> 
> Cheers,
> Andreas


-- 
Andreas K. Hüttel
dilfridge@gentoo.org
Gentoo Linux developer
(council, toolchain, base-system, perl, libreoffice)

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Re: [gentoo-dev] Announcing RISC-V

[Michał Górny]

On Fri, 2019-05-03 at 23:34 +0200, Andreas K. Huettel wrote:
> * We will initially add two profiles to profile.desc: 
>   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit hardfloat)
>   default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, i.e. hard/softfloat)

I still don't understand the purpose of this multilib.  If you have
a hardfloat CPU, why would you ever build some of the software
softfloat?


-- 
Best regards,
Michał Górny

Re: [gentoo-dev] Announcing RISC-V

[Andrew Savchenko]

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On Sat, 18 May 2019 20:47:28 +0200 Michał Górny wrote:
> On Fri, 2019-05-03 at 23:34 +0200, Andreas K. Huettel wrote:
> > * We will initially add two profiles to profile.desc: 
> >   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit hardfloat)
> >   default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, i.e. hard/softfloat)
> 
> I still don't understand the purpose of this multilib.  If you have
> a hardfloat CPU, why would you ever build some of the software
> softfloat?

One may have binary-only software which requires softfloat
dependencies.

Best regards,
Andrew Savchenko

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Re: [gentoo-dev] Announcing RISC-V

[Michał Górny]

On Sat, 2019-05-18 at 22:34 +0300, Andrew Savchenko wrote:
> On Sat, 18 May 2019 20:47:28 +0200 Michał Górny wrote:
> > On Fri, 2019-05-03 at 23:34 +0200, Andreas K. Huettel wrote:
> > > * We will initially add two profiles to profile.desc: 
> > >   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit hardfloat)
> > >   default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, i.e. hard/softfloat)
> > 
> > I still don't understand the purpose of this multilib.  If you have
> > a hardfloat CPU, why would you ever build some of the software
> > softfloat?
> 
> One may have binary-only software which requires softfloat
> dependencies.
> 

I'd like to see such software for riscv.

-- 
Best regards,
Michał Górny

Re: [gentoo-dev] Announcing RISC-V

[William Hubbs]

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On Sat, May 18, 2019 at 09:45:15PM +0200, Michał Górny wrote:
> On Sat, 2019-05-18 at 22:34 +0300, Andrew Savchenko wrote:
> > On Sat, 18 May 2019 20:47:28 +0200 Michał Górny wrote:
> > > On Fri, 2019-05-03 at 23:34 +0200, Andreas K. Huettel wrote:
> > > > * We will initially add two profiles to profile.desc: 
> > > >   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit hardfloat)
> > > >   default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64, i.e. hard/softfloat)
> > > 
> > > I still don't understand the purpose of this multilib.  If you have
> > > a hardfloat CPU, why would you ever build some of the software
> > > softfloat?
> > 
> > One may have binary-only software which requires softfloat
> > dependencies.
> > 
> 
> I'd like to see such software for riscv.

I'm curious myself, just because I don't know this architecture.
Is there prebuilt software like this, or are we just supporting some
theoretical option that we don't know for sure exists?

Thanks,

William


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Re: [gentoo-dev] Announcing RISC-V

[Alexis Ballier]

On Sat, 18 May 2019 20:47:28 +0200
Michał Górny <mgorny@gentoo.org> wrote:

> On Fri, 2019-05-03 at 23:34 +0200, Andreas K. Huettel wrote:
> > * We will initially add two profiles to profile.desc: 
> >   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit
> > hardfloat) default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64,
> > i.e. hard/softfloat)
> 
> I still don't understand the purpose of this multilib.  If you have
> a hardfloat CPU, why would you ever build some of the software
> softfloat?


One reason I could imagine is that the hardfloat isn't IEEE 754
compliant. Searching through the RISC-V spec, it does not seem to be
the case here (ie: it is required to be compliant) so I'm also
wondering what is the point here.


Note that hard vs soft float will be the least of our concerns
here: Based on wikipedia, I count 4 base ISA (2 stable, 2 dev) and 13
optional extensions (6 stable, 7 dev) so we potentially have an
exponential number of ABIs here...

Re: [gentoo-dev] Announcing RISC-V

[Alexis Ballier]

On Wed, 29 May 2019 10:27:34 -0700 (PDT)
Palmer Dabbelt <palmer@sifive.com> wrote:

> On Mon, 20 May 2019 02:44:18 PDT (-0700), aballier@gentoo.org wrote:
> > On Sat, 18 May 2019 20:47:28 +0200
> > Michał Górny <mgorny@gentoo.org> wrote:
> >
> >> On Fri, 2019-05-03 at 23:34 +0200, Andreas K. Huettel wrote:
> >> > * We will initially add two profiles to profile.desc: 
> >> >   default/linux/riscv/17.0/rv64gc/lp64d (non-multilib, 64bit
> >> > hardfloat) default/linux/riscv/17.0/rv64gc (multilib lp64d/lp64,
> >> > i.e. hard/softfloat)
> >> 
> >> I still don't understand the purpose of this multilib.  If you have
> >> a hardfloat CPU, why would you ever build some of the software
> >> softfloat?
> >
> > One reason I could imagine is that the hardfloat isn't IEEE 754
> > compliant. Searching through the RISC-V spec, it does not seem to be
> > the case here (ie: it is required to be compliant) so I'm also
> > wondering what is the point here.
> 
> The RISC-V floating-point extensions are IEEE-754 compliant, but
> they're optional.  We have chips without floating-point units, but
> right now all the Linux capable chips have FPUs.  As far as I know
> there are no Linux binaries that anyone cares about that are compiled
> for systems without hardware floating-point units, but I may be wrong
> about that one.


It was my understanding that FPU is not optional for rv64gc, is that
correct ?

> The non-FPU systems are much more interesting in embedded land, where
> lots of users don't have FPUs.  That's less relevant for Gentoo, but
> I do use crossdev embedded toolchains.


You'll probably not be using multilib here but rather a specific CHOST
and/or flags to enable softfloat everywhere.


[...]


Alexis.