GSOC 2018 ARM Cortex Processor

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GSOC 2018 ARM Cortex Processor

Vishal Gupta
Hi,
I am interested in working on the project to port FreeBSD to ARM Cortex M
or R series microprocessor. Some queries related to the project are :-
1) What are the expected deliverable for the project.
2) Where to put my draft proposal for review so that it can be improved.

An early reply is awaited.

Thanks and regards,
Vishal Gupta
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Re: GSOC 2018 ARM Cortex Processor

Michael Zhilin
Hi,

Disclaimer: I'm neither ARM expect nor GSoC person.

I may be wrong, but FreeBSD (or Linux, doesn't matter) requires MMU which
is missing in Cortex M/R family of ARM processors. So it's technically
difficult/impossible to port it on non-MMU processor.

Added freebsd-arm@ for wide audience.

Thank you!



On Tue, Mar 13, 2018 at 1:12 PM, Vishal Gupta <[hidden email]>
wrote:

> Hi,
> I am interested in working on the project to port FreeBSD to ARM Cortex M
> or R series microprocessor. Some queries related to the project are :-
> 1) What are the expected deliverable for the project.
> 2) Where to put my draft proposal for review so that it can be improved.
>
> An early reply is awaited.
>
> Thanks and regards,
> Vishal Gupta
> _______________________________________________
> [hidden email] mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-embedded
> To unsubscribe, send any mail to "[hidden email]
> "
>
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Re: GSOC 2018 ARM Cortex Processor

Warner Losh
There's not currently any other FreeBSD port that works on a system without
a MMU. The buffer cache assumes that we can fault in pages as needed based
on virtual address access. The TEXT sharing between programs assumes we can
map the same page into multiple processes. The shared libraries we have
assume something similar, and in some cases copy on write on top of that
(though that's no different from a HW perspective than these first few
cases).

So, if you're willing to live without these features, or find some other
way to accomplish the same sorts of things, a cortex M/R port would be
tricky. Also, FreeBSD's kernel size may present some obstacles. We're
optimized for a rich memory environment, so we trade extra copies of code
to speed up execution of code, which matches the x86 market, as well as the
high-end of embedded quite well.

If you are looking for a BSD to port to these processors, you might
consider looking at what www.retrobsd.org has done with their 2.11BSD port
to the MIPS processor in the PIC32 core with the MIPS M4K architecture. It
runs in as little as 128k of RAM, while FreeBSD these days needs at least
128MB of RAM without careful tuning...

Warner

On Tue, Mar 13, 2018 at 12:07 AM, Michael Zhilin <[hidden email]> wrote:

> Hi,
>
> Disclaimer: I'm neither ARM expect nor GSoC person.
>
> I may be wrong, but FreeBSD (or Linux, doesn't matter) requires MMU which
> is my tossing in Cortex M/R family of ARM processors. So it's technically
> difficult/impossible to port it on non-MMU processor.
>
> Added freebsd-arm@ for wide audience.
>
> Thank you!
>
>
>
> On Tue, Mar 13, 2018 at 1:12 PM, Vishal Gupta <[hidden email]>
> wrote:
>
> > Hi,
> > I am interested in working on the project to port FreeBSD to ARM Cortex M
> > or R series microprocessor. Some queries related to the project are :-
> > 1) What are the expected deliverable for the project.
> > 2) Where to put my draft proposal for review so that it can be improved.
> >
> > An early reply is awaited.
> >
> > Thanks and regards,
> > Vishal Gupta
> > _______________________________________________
> > [hidden email] mailing list
> > https://lists.freebsd.org/mailman/listinfo/freebsd-embedded
> > To unsubscribe, send any mail to "freebsd-embedded-unsubscribe@
> freebsd.org
> > "
> >
> _______________________________________________
> [hidden email] mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-embedded
> To unsubscribe, send any mail to "[hidden email]
> "
>
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Re: GSOC 2018 ARM Cortex Processor

Vishal Gupta
Thank you for the reply.
Which new processor would you suggest between PowerPC, ARM, and MIPS which
i can port during the summer period and will also be useful for the
community.

Vishal Gupta

On Tue, Mar 13, 2018 at 11:52 AM, Warner Losh <[hidden email]> wrote:

> There's not currently any other FreeBSD port that works on a system
> without a MMU. The buffer cache assumes that we can fault in pages as
> needed based on virtual address access. The TEXT sharing between programs
> assumes we can map the same page into multiple processes. The shared
> libraries we have assume something similar, and in some cases copy on write
> on top of that (though that's no different from a HW perspective than these
> first few cases).
>
> So, if you're willing to live without these features, or find some other
> way to accomplish the same sorts of things, a cortex M/R port would be
> tricky. Also, FreeBSD's kernel size may present some obstacles. We're
> optimized for a rich memory environment, so we trade extra copies of code
> to speed up execution of code, which matches the x86 market, as well as the
> high-end of embedded quite well.
>
> If you are looking for a BSD to port to these processors, you might
> consider looking at what www.retrobsd.org has done with their 2.11BSD
> port to the MIPS processor in the PIC32 core with the MIPS M4K
> architecture. It runs in as little as 128k of RAM, while FreeBSD these days
> needs at least 128MB of RAM without careful tuning...
>
> Warner
>
> On Tue, Mar 13, 2018 at 12:07 AM, Michael Zhilin <[hidden email]> wrote:
>
>> Hi,
>>
>> Disclaimer: I'm neither ARM expect nor GSoC person.
>>
>> I may be wrong, but FreeBSD (or Linux, doesn't matter) requires MMU which
>> is my tossing in Cortex M/R family of ARM processors. So it's technically
>> difficult/impossible to port it on non-MMU processor.
>>
>> Added freebsd-arm@ for wide audience.
>>
>> Thank you!
>>
>>
>>
>> On Tue, Mar 13, 2018 at 1:12 PM, Vishal Gupta <[hidden email]>
>> wrote:
>>
>> > Hi,
>> > I am interested in working on the project to port FreeBSD to ARM Cortex
>> M
>> > or R series microprocessor. Some queries related to the project are :-
>> > 1) What are the expected deliverable for the project.
>> > 2) Where to put my draft proposal for review so that it can be improved.
>> >
>> > An early reply is awaited.
>> >
>> > Thanks and regards,
>> > Vishal Gupta
>> > _______________________________________________
>> > [hidden email] mailing list
>> > https://lists.freebsd.org/mailman/listinfo/freebsd-embedded
>> > To unsubscribe, send any mail to "freebsd-embedded-unsubscribe@
>> freebsd.org
>> > "
>> >
>> _______________________________________________
>> [hidden email] mailing list
>> https://lists.freebsd.org/mailman/listinfo/freebsd-embedded
>> To unsubscribe, send any mail to "freebsd-embedded-unsubscribe@
>> freebsd.org"
>>
>
>
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Re: GSOC 2018 ARM Cortex Processor

Konstantin Belousov
In reply to this post by Warner Losh
On Tue, Mar 13, 2018 at 12:22:03AM -0600, Warner Losh wrote:
> There's not currently any other FreeBSD port that works on a system without
> a MMU. The buffer cache assumes that we can fault in pages as needed based
> on virtual address access. The TEXT sharing between programs assumes we can
No, buffer cache does not fault the pages in, but it is indeed relies
somewhat on ability to remap pages.  This is true for B_VMIO buffers,
not for the malloc-ed buffers.

> map the same page into multiple processes. The shared libraries we have
> assume something similar, and in some cases copy on write on top of that
> (though that's no different from a HW perspective than these first few
> cases).
>
> So, if you're willing to live without these features, or find some other
> way to accomplish the same sorts of things, a cortex M/R port would be
> tricky. Also, FreeBSD's kernel size may present some obstacles. We're
> optimized for a rich memory environment, so we trade extra copies of code
> to speed up execution of code, which matches the x86 market, as well as the
> high-end of embedded quite well.
Living without the listed features means, in essence, that userspace
cannot be even started. Which, in fact, is not that fatal for the
applications where -R cores are supposed to be used. If kernel-only
operations are enough, or the application is adopted to be run as part
of the kernel, it might be quite fun project to take.
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Re: GSOC 2018 ARM Cortex Processor

Mori Hiroki
In reply to this post by Vishal Gupta
Hi

Realtek is very strange company.

RTL8197D -- Lexra base
RTL8197F -- MIPS 24K base

I think we must not support Lexra type soc.
Because of that instruction is very old.

But Realtek make new MIPS 24K base soc.
That support is good.

Regards

Hiroki Mori


----- Original Message -----

> From: Michael Zhilin <[hidden email]>
> To: Vishal Gupta <[hidden email]>
> Cc: "[hidden email]" <[hidden email]>; "[hidden email]" <[hidden email]>; [hidden email]
> Date: 2018/3/14, Wed 15:39
> Subject: Re: GSOC 2018 ARM Cortex Processor
>
> Added freebsd-mips@
>
> Regarding MIPS, I would like to see support for retail Realtek MIPS chips
> for instance (RTL8196, RTL8197). There are new brand router models:
> https://wikidevi.com/wiki/Tenda_AC6_V2 or
> https://wikidevi.com/wiki/Realtek#bgn_2
>
> Thanks!
>
> On Tue, Mar 13, 2018 at 4:49 PM, Vishal Gupta <[hidden email]>
> wrote:
>
>>  Thank you for the reply.
>>  Which new processor would you suggest between PowerPC, ARM, and MIPS
>>  which i can port during the summer period and will also be useful for the
>>  community.
>>
>>  Vishal Gupta
>>
>>  On Tue, Mar 13, 2018 at 11:52 AM, Warner Losh <[hidden email]> wrote:
>>
>>>  There's not currently any other FreeBSD port that works on a system
>>>  without a MMU. The buffer cache assumes that we can fault in pages as
>>>  needed based on virtual address access. The TEXT sharing between
> programs
>>>  assumes we can map the same page into multiple processes. The shared
>>>  libraries we have assume something similar, and in some cases copy on
> write
>>>  on top of that (though that's no different from a HW perspective
> than these
>>>  first few cases).
>>>
>>>  So, if you're willing to live without these features, or find some
> other
>>>  way to accomplish the same sorts of things, a cortex M/R port would be
>>>  tricky. Also, FreeBSD's kernel size may present some obstacles.
> We're
>>>  optimized for a rich memory environment, so we trade extra copies of
> code
>>>  to speed up execution of code, which matches the x86 market, as well as
> the
>>>  high-end of embedded quite well.
>>>
>>>  If you are looking for a BSD to port to these processors, you might
>>>  consider looking at what www.retrobsd.org has done with their 2.11BSD
>>>  port to the MIPS processor in the PIC32 core with the MIPS M4K
>>>  architecture. It runs in as little as 128k of RAM, while FreeBSD these
> days
>>>  needs at least 128MB of RAM without careful tuning...
>>>
>>>  Warner
>>>
>>>  On Tue, Mar 13, 2018 at 12:07 AM, Michael Zhilin
> <[hidden email]>
>>>  wrote:
>>>
>>>>  Hi,
>>>>
>>>>  Disclaimer: I'm neither ARM expect nor GSoC person.
>>>>
>>>>  I may be wrong, but FreeBSD (or Linux, doesn't matter) requires
> MMU which
>>>>  is my tossing in Cortex M/R family of ARM processors. So it's
> technically
>>>>  difficult/impossible to port it on non-MMU processor.
>>>>
>>>>  Added freebsd-arm@ for wide audience.
>>>>
>>>>  Thank you!
>>>>
>>>>
>>>>
>>>>  On Tue, Mar 13, 2018 at 1:12 PM, Vishal Gupta
> <[hidden email]
>>>>  >
>>>>  wrote:
>>>>
>>>>  > Hi,
>>>>  > I am interested in working on the project to port FreeBSD to
> ARM
>>>>  Cortex M
>>>>  > or R series microprocessor. Some queries related to the
> project are :-
>>>>  > 1) What are the expected deliverable for the project.
>>>>  > 2) Where to put my draft proposal for review so that it can be
>>>>  improved.
>>>>  >
>>>>  > An early reply is awaited.
>>>>  >
>>>>  > Thanks and regards,
>>>>  > Vishal Gupta
>>>>  > _______________________________________________
>>>>  > [hidden email] mailing list
>>>>  > https://lists.freebsd.org/mailman/listinfo/freebsd-embedded
>>>>  > To unsubscribe, send any mail to
> "freebsd-embedded-unsubscribe@
>>>>  freebsd.org
>>>>  > "
>>>>  >
>>>>  _______________________________________________
>>>>  [hidden email] mailing list
>>>>  https://lists.freebsd.org/mailman/listinfo/freebsd-embedded
>>>>  To unsubscribe, send any mail to
> "freebsd-embedded-unsubscribe@
>>>>  freebsd.org"
>>>>
>>>
>>>
>>
> _______________________________________________
> [hidden email] mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-arm
> To unsubscribe, send any mail to "[hidden email]"
>
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