[Bug 1001186] New: Introduce Cortex-M4 to the Cortex-M architecture

[Bug 1001186] New: Introduce Cortex-M4 to the Cortex-M architecture

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           Summary: Introduce Cortex-M4 to the Cortex-M architecture
           Product: eCos
           Version: 3.0
          Platform: Other (please specify)
        OS/Version: Cortex-M
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: low
         Component: Patches and contributions
        AssignedTo: unassigned@bugs.ecos.sourceware.org
        ReportedBy: ilijak@siva.com.mk
                CC: ecos-patches@ecos.sourceware.org
             Class: Advice Request


Created an attachment (id=1197)
 --> (http://bugs.ecos.sourceware.org/attachment.cgi?id=1197)
Cortex-M4 macro

Cortex-M4 is introduced to Cortex-M architecture:
  - M4 added to CYGHWR_HAL_CORTEXM legal values
  - CYGHWR_HAL_CORTEXM_M4 used in preprocessor conditions where applicable.
  - Added Floating Point Unit option and interface to cortexm.cdl

Also added M0 to CYGHWR_HAL_CORTEXM legal values.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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Ilija Kocho <ilijak@siva.com.mk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |1001187

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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Sergei Gavrikov <sergei.gavrikov@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Attachment #1197|0                           |1
        is obsolete|                            |

--- Comment #1 from Sergei Gavrikov <sergei.gavrikov@gmail.com> 2011-04-05 19:33:39 BST ---
Created an attachment (id=1203)
 --> (http://bugs.ecos.sourceware.org/attachment.cgi?id=1203)
cortexm: intro M0, M4

Cleaned-up version of Attachment 1197.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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--- Comment #2 from Sergei Gavrikov <sergei.gavrikov@gmail.com> 2011-04-05 19:38:56 BST ---
As for me it would be applied, but, as it is eCos arch. layer, the expert
opinions and comments are welcome.

Sergei

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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Nick Garnett <nickg@ecoscentric.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nickg@ecoscentric.com

--- Comment #3 from Nick Garnett <nickg@ecoscentric.com> 2011-04-06 14:15:25 BST ---
The M4 stuff looks OK to me.

However, I am not sure that we need the M0 option. The v6-M architecture is a
severely cut down version of the v7-M architecture. It lacks a lot of the
features we currently use in the Cortex-M HAL. Things like the dual stack
pointers, SVC, PendSVC and SysTick are only available if the OS option is
enabled. Other things like the programmable vector table base address and the
BASEPRI register are entirely absent.

Adding M0 to the list would raise entirely false expectations that this
processor type was supported. In fact, I would prefer to remove M1, since these
parts have the same problems.

We would have to do quite a lot of work to support M0/1. Given that these parts
are targeted at very low resource systems, I doubt that there will ever be much
demand for eCos on these.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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--- Comment #4 from Sergei Gavrikov <sergei.gavrikov@gmail.com> 2011-04-06 16:42:30 BST ---
(In reply to comment #3)
> The M4 stuff looks OK to me.
> 
> However, I am not sure that we need the M0 option. 

[snip]

> Adding M0 to the list would raise entirely false expectations that this
> processor type was supported. In fact, I would prefer to remove M1, since
> these parts have the same problems.
> 
> We would have to do quite a lot of work to support M0/1. Given that these
> parts are targeted at very low resource systems, I doubt that there will
> ever be much demand for eCos on these.

Nick, thank you for your expert look and explanation. So then, should I
reject the M0 (and M1?) mentions from the cortexm config file?

Ilija, do you have M0-claim for your present ports? If you have not,
I'll fix the patch too.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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--- Comment #5 from Nick Garnett <nickg@ecoscentric.com> 2011-04-06 16:55:13 BST ---
(In reply to comment #4)

> Nick, thank you for your expert look and explanation. So then, should I
> reject the M0 (and M1?) mentions from the cortexm config file?

My opinion is that we should not add M0, and I think M1 should be removed until
we have real support for that variant. I added M1 to the list early on in
development, before I fully understood the actual differences between the v6-M
and v7-M architectures.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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--- Comment #6 from Ilija Kocho <ilijak@siva.com.mk> 2011-04-06 17:07:45 BST ---
(In reply to comment #5)
> (In reply to comment #4)
> 
> > Nick, thank you for your expert look and explanation. So then, should I
> > reject the M0 (and M1?) mentions from the cortexm config file?
> 
> My opinion is that we should not add M0, and I think M1 should be removed until
> we have real support for that variant. I added M1 to the list early on in
> development, before I fully understood the actual differences between the v6-M
> and v7-M architectures.

Thank you for your review Nick. I had the same concerns regarding M0 and I
added it mainly because of presence of M1. I agree with you to omit M0 and M1.
Should anybody decide to port eCos to M0/M1 the easiest part of the job is to
put an entry in the legal values.

Note: Also we have to change the description. I propose to keep only offered
values (M3 M4) there too.

If you agree and this is all I could prepare a new patch for review.

Ilija.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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--- Comment #7 from Sergei Gavrikov <sergei.gavrikov@gmail.com> 2011-04-06 17:14:54 BST ---
(In reply to comment #6)
> If you agree and this is all I could prepare a new patch for review.
> 
> Ilija.

Ilija, I have run my $EDITOR already, so we will not duplicate our
efforts :-)

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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--- Comment #8 from Ilija Kocho <ilijak@siva.com.mk> 2011-04-06 17:19:56 BST ---
(In reply to comment #7)
> (In reply to comment #6)
> > If you agree and this is all I could prepare a new patch for review.
> > 
> > Ilija.
> 
> Ilija, I have run my $EDITOR already, so we will not duplicate our
> efforts :-)

OK, Thanks. Go ahead.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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Sergei Gavrikov <sergei.gavrikov@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Attachment #1203|0                           |1
        is obsolete|                            |

--- Comment #9 from Sergei Gavrikov <sergei.gavrikov@gmail.com> 2011-04-06 17:31:39 BST ---
Created an attachment (id=1205)
 --> (http://bugs.ecos.sourceware.org/attachment.cgi?id=1205)
cortexm:arch: remove M1, add M4 CPU families

Follows the comment #3, comment #5.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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--- Comment #10 from Nick Garnett <nickg@ecoscentric.com> 2011-04-06 17:40:48 BST ---
The new patch looks good to me. Go for it.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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--- Comment #11 from Sergei Gavrikov <sergei.gavrikov@gmail.com> 2011-04-06 17:57:53 BST ---
(In reply to comment #10)
> The new patch looks good to me. Go for it.

Checked-in.

All, thank you.

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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Sergei Gavrikov <sergei.gavrikov@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |sergei.gavrikov@gmail.com
            Version|3.0                         |CVS
         Resolution|                            |CURRENTRELEASE

--- Comment #12 from Sergei Gavrikov <sergei.gavrikov@gmail.com> 2011-04-06 17:59:20 BST ---
RESOLVED (in CVS).

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[Bug 1001186] Introduce Cortex-M4 to the Cortex-M architecture

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--- Comment #13 from Ilija Kocho <ilijak@siva.com.mk> 2011-04-06 18:09:35 BST ---
(In reply to comment #11)
> (In reply to comment #10)
> > The new patch looks good to me. Go for it.
> 
> Checked-in.
> 
> All, thank you.

Sergei, Nick
Many thanks.

Ilija

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