[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Peter Pearse]

> -----Original Message-----
> From: Peter Pearse [mailto:peter.pearse at arm.com] 
> Sent: 14 February 2008 13:59
> To: 'wd at denx.de'
> Subject: RE: [U-Boot-Users] [PATCH][ARM] Rationalize ARM 
> compiler options
> 
> 
> > -----Original Message-----
> > From: wd at denx.de [mailto:wd at denx.de]
> > Sent: 13 February 2008 22:51
> > To: Peter Pearse
> > Cc: U-Boot-Users
> > Subject: Re: [U-Boot-Users] [PATCH][ARM] Rationalize ARM compiler 
> > options
> > 
> > 
> > Please don't add too many empty lines.
> >
> 
> OK - I'll change thie when I re-submit. 
> I just like to be able to ripple thru my buffers to animate 
> the differences between almost identical files.
>  
> > Why exactly are you dropping -msoft-float here?
> 
> I was under the delusion that dropping this protected against 
> incorporation of floating point instructions. 
> 
> Have I now got a clear understanding of the position:-
> 
> "
> The use of floating point arithmetic in the U-Boot code is 
> deprecated. 
> However the ELDK toolchains provide floating point support 
> and were built with the -msoft-float option. This option is 
> supplied to the code to ensure any floating point arithmetic 
> included links in the floating point support code correctly. 
> " 
> 
> If so I'll put -msoft-float in all arm config.mk files.
> 
> > 
> > > -# Make ARMv5 to allow more compilers to work, even though its v6.
> > > -PLATFORM_CPPFLAGS += -march=armv5
> > > +PLATFORM_CPPFLAGS += -march=armv6
> > 
> > Why exactly are you changing this?
> 
> arm1136 is an ARM Architecture V6 processor.
> 
> My position is:
> "
> The main (arm) tree processor options should use the correct 
> architecture option for the processor (provided this option 
> is accepted without error or warning  by the ELDK arm 
> toolchains) Users using compilers which do not support the 
> correct architecture should be made aware of this.
> Should they wish to use another compiler they can change this 
> option locally.  
> "
> 
> I would also accept
> (reluctantly, although it saves lots of space I could waste 
> as empty lines ;-) )
> 
> "
> For simplicity, the main (arm) tree processor options use the 
> lowest common architecture option (armv4), whatever the 
> processor implements. Users can change this option locally.  
> "
> 
> At present we have a mixture.....
> 
> Regards
> 
> Peter
> 
> 

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Haavard Skinnemoen]

On Mon, 18 Feb 2008 09:20:18 -0000
"Peter Pearse" <peter.pearse@arm.com> wrote:

> > The use of floating point arithmetic in the U-Boot code is 
> > deprecated.

I'd say it's more than deprecated -- we shouldn't be using floating
point arithmetic at all in u-boot. IMNSHO.

Haavard

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Wolfgang Denk]

In message <20080218123300.5dfd6e56@dhcp-252-066.norway.atmel.com> you wrote:
> On Mon, 18 Feb 2008 09:20:18 -0000
> "Peter Pearse" <peter.pearse@arm.com> wrote:
> 
> > > The use of floating point arithmetic in the U-Boot code is 
> > > deprecated.
> 
> I'd say it's more than deprecated -- we shouldn't be using floating
> point arithmetic at all in u-boot. IMNSHO.

ACK. FP is forbidden. Period.

You may use FP in your standalone applications, but at your own  risk
and without any explicit support from the underlying U-Boot code.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
If the facts don't fit the theory, change the facts.
                                                   -- Albert Einstein

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Ulf Samuelsson]

>> > 
>> > Please don't add too many empty lines.
>> >
>> 
>> OK - I'll change thie when I re-submit. 
>> I just like to be able to ripple thru my buffers to animate 
>> the differences between almost identical files.
>>  
>> > Why exactly are you dropping -msoft-float here?
>> 
>> I was under the delusion that dropping this protected against 
>> incorporation of floating point instructions. 
>> 
>> Have I now got a clear understanding of the position:-
>> 
>> "
>> The use of floating point arithmetic in the U-Boot code is 
>> deprecated. 
>> However the ELDK toolchains provide floating point support 
>> and were built with the -msoft-float option. This option is 
>> supplied to the code to ensure any floating point arithmetic 
>> included links in the floating point support code correctly. 
>> " 
>> 
>> If so I'll put -msoft-float in all arm config.mk files.

Please DON'T!
This *forces* you to compile U-Boot with a compiler suite which is
configured to generate soft-float.
If you happen to use a compiler which does not support soft-float,
I.E: uses NWFPE, then the build will fail.

Also what happens if you have a toolchain built without V5 support?
Will the build complete?

>> 
>> > 
>> > > -# Make ARMv5 to allow more compilers to work, even though its v6.
>> > > -PLATFORM_CPPFLAGS += -march=armv5
>> > > +PLATFORM_CPPFLAGS += -march=armv6
>> > 
>> > Why exactly are you changing this?
>> 
>> arm1136 is an ARM Architecture V6 processor.
>> 
>> My position is:
>> "
>> The main (arm) tree processor options should use the correct 
>> architecture option for the processor (provided this option 
>> is accepted without error or warning  by the ELDK arm 
>> toolchains) Users using compilers which do not support the 
>> correct architecture should be made aware of this.
>> Should they wish to use another compiler they can change this 
>> option locally.
>> "

Why not make this user tunable.
If you want to mess about with V4 vs V5 support you should,
but don't enforce this for people that could care less.

>> I would also accept
>> (reluctantly, although it saves lots of space I could waste 
>> as empty lines ;-) )
>> 
>> "
>> For simplicity, the main (arm) tree processor options use the 
>> lowest common architecture option (armv4), whatever the 
>> processor implements. Users can change this option locally.  
>> "
>> 
>> At present we have a mixture.....
>> 
>> Regards
>> 
>> Peter
>> 


Best Regards
Ulf Samuelsson

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Wolfgang Denk]

In message <9a3001c872b7$dc147910$0402a8c0@atmel.com> you wrote:
> 
> >> If so I'll put -msoft-float in all arm config.mk files.
> 
> Please DON'T!
> This *forces* you to compile U-Boot with a compiler suite which is
> configured to generate soft-float.

I think this is not correct. Even if your compiler is not configured
to generate soft-float by default, asking it to do so should cause no
harm.

> If you happen to use a compiler which does not support soft-float,
> I.E: uses NWFPE, then the build will fail.

Even if it's configured for NWFPE as default setting, it should still
be able to generate soft-float. 

And in the end, it should make no differece at all as we don't use FP
in U-Boot.


Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
If I ever needed a brain transplant, I'd choose a teenager's  because
I'd want a brain that had never been used.

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Ulf Samuelsson]

> In message <9a3001c872b7$dc147910$0402a8c0@atmel.com> you wrote:
>> 
>> >> If so I'll put -msoft-float in all arm config.mk files.
>> 
>> Please DON'T!
>> This *forces* you to compile U-Boot with a compiler suite which is
>> configured to generate soft-float.
> 
> I think this is not correct. Even if your compiler is not configured
> to generate soft-float by default, asking it to do so should cause no
> harm.

In this case, reality and the map differs.
NWFPE toolchains built by cross-tool, buildroot, and www.gnuarm.com
not sure abnout the last) all bombs when they reach the "-msoft-float"

> 
>> If you happen to use a compiler which does not support soft-float,
>> I.E: uses NWFPE, then the build will fail.
> 
> Even if it's configured for NWFPE as default setting, it should still
> be able to generate soft-float. 

It doesn't.
If you think so, show me an ARM toolset which behaves in this way.

> And in the end, it should make no differece at all as we don't use FP
> in U-Boot.
> 

Without "-msoft-float", both the softfloat and NWFPE toolchains
will complete the build since floating point is not used..
With "-msoft-float", NWFPE based toolchains for ARM appears to abort.

If it doesn't make any difference, and U-Boot does not use floating point
then it make sense to remove all  "-msoft-float" for ARM Makefiles.'

It is so easy to replace all fixed parameters with symbolic Makefile variable
which can be modified by your make command

$ make "MYPARS=-msoft-float" uboot

With sensible defaults which can be overriddern, this would solve the problem, 
without having to locally *patch* the source.
When you are building several u-boots for different ARM chips
from the same source you really do not want to patch the source.

> 
> Best regards,
> 
> Wolfgang Denk
> 


Best Regards
Ulf Samuelsson                ulf at atmel.com
Atmel Nordic AB
Mail:  Box 2033, 174 02 Sundbyberg, Sweden
Visit:  Kavalleriv?gen 24, 174 58 Sundbyberg, Sweden
Phone +46 (8) 441 54 22     Fax +46 (8) 441 54 29
GSM    +46 (706) 22 44 57

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Haavard Skinnemoen]

On Wed, 20 Feb 2008 07:33:47 +0100
"Ulf Samuelsson" <ulf@atmel.com> wrote:

> In this case, reality and the map differs.
> NWFPE toolchains built by cross-tool, buildroot, and www.gnuarm.com
> not sure abnout the last) all bombs when they reach the "-msoft-float"

You mean they don't recognize -msoft-float as an option? If so,

CFLAGS += $(call cc-option,-msoft-float)

should do the right thing, no?

Haavard

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Ulf Samuelsson]

> On Wed, 20 Feb 2008 07:33:47 +0100
> "Ulf Samuelsson" <ulf@atmel.com> wrote:
> 
>> In this case, reality and the map differs.
>> NWFPE toolchains built by cross-tool, buildroot, and www.gnuarm.com
>> not sure abnout the last) all bombs when they reach the "-msoft-float"
> 
> You mean they don't recognize -msoft-float as an option? 

Not the one's I have tried.

> If so,
> 
> CFLAGS += $(call cc-option,-msoft-float)
> 
> should do the right thing, no?
> 
> Haavard
>

Looks OK to me, but I never used "call cc-option".

I think there are a multitude of possibilities, unless the goal is to ensure 
that anyone trying something else than ELDK will run into trouble.

Best Regards
Ulf Samuelsson

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Haavard Skinnemoen]

On Wed, 20 Feb 2008 18:58:27 +0100
"Ulf Samuelsson" <ulf@atmel.com> wrote:

> Looks OK to me, but I never used "call cc-option".

cc-option will try to run the compiler with the option. If the compiler
didn't complain, it evaluates to the option. If it failed, it evaluates
to nothing.

Very useful if you want to introduce new compiler options without
breaking compatibility with old or weird compilers. The Linux build
system uses it all over the place -- I suspect we could prevent quite a
few toolchain incompatibilies by using it more extensively in u-boot as
well.

Of course, it won't help you if the compiler misbehaves in other ways
than just refusing to accept the option.

Haavard

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Peter Pearse]

 

> -----Original Message-----
> From: Ulf Samuelsson [mailto:ulf.samuelsson at atmel.com] 
> Sent: 20 February 2008 00:40
> To: Peter Pearse
> Subject: Re: [U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM 
> compiler options
> 
---snip---

> > 
> > My postion remains that U-Boot is supplied to build with the latest 
> > ELDK toolchain.
> > Supporting all possible toolchains (and all possible builds of those
> > toolchains)
> > is too much effort.
> 
> Since I have already implemented a fix in my private U-boot I 
> know this to be false (at least for this specific problem).
> 

I'm not clear here - are you saying that the arm compiler options,
in the current U-Boot head, prevent one or more boards building with 

arm-linux-gcc (GCC) 4.0.0 (DENX ELDK 4.1.4.0.0) 

(excluding build systems which treat all warnings as errors)?

If so, please supply details.

Regards

Peter

[U-Boot-Users] FW: [PATCH][ARM] Rationalize ARM compiler options

[Ulf Samuelsson]

> ---snip---
> 
>> > 
>> > My postion remains that U-Boot is supplied to build with the latest 
>> > ELDK toolchain.
>> > Supporting all possible toolchains (and all possible builds of those
>> > toolchains)
>> > is too much effort.
>> 
>> Since I have already implemented a fix in my private U-boot I 
>> know this to be false (at least for this specific problem).
>> 
> 
> I'm not clear here - are you saying that the arm compiler options,
> in the current U-Boot head, prevent one or more boards building with 
> 
> arm-linux-gcc (GCC) 4.0.0 (DENX ELDK 4.1.4.0.0) 
> 

No, I am saying that these options prevent U-Boot to be built
by most things except ELDK, and that removing the "-msoft-float"
should allow U-boot to be built by basically anything.

I also think that there is no reason to force someone to use
architecture specific tuning, but that U-boot should allow
for people to apply this.

> (excluding build systems which treat all warnings as errors)?
> 
> If so, please supply details.
> 
> Regards
> 
> Peter
> 


Best Regards
Ulf Samuelsson                ulf at atmel.com
Atmel Nordic AB
Mail:  Box 2033, 174 02 Sundbyberg, Sweden
Visit:  Kavalleriv?gen 24, 174 58 Sundbyberg, Sweden
Phone +46 (8) 441 54 22     Fax +46 (8) 441 54 29
GSM    +46 (706) 22 44 57