Building libm library

Building libm library

[Harish]

Hi newlib,

I would like to build just libm.a library, is it possible? if yes, please
let me know how can I do it.


Thanks,
Harish C

Re: Building libm library

[Jeff Johnston]

Hello Harish,

It isn't supported.  There are no top Makefile targets for you to do this
and building targets directly from Makefiles in subdirectories often
runs into issues (e.g. missing headers that haven't been copied or
paths/vars set incorrectly since they are supposed to be set by parent
Makefiles).
In addition, the errno/reentrant mechanisms used by libm.a are supplied by
libc.a.

-- Jeff J.

On Thu, Jul 15, 2021 at 7:44 AM Harish <harishcse44@gmail.com> wrote:

> Hi newlib,
>
> I would like to build just libm.a library, is it possible? if yes, please
> let me know how can I do it.
>
>
> Thanks,
> Harish C
>
>

Re: Building libm library

[Harish]

Ok, thanks for the clarification. One more question. I would like to use
math library on a baremetal and want to know if the newlib math library
uses system calls?. If yes, is there any other implementation which can be
used for baremetals?

Regards,
Harish

On Thu, 15 Jul, 2021, 11:19 pm Jeff Johnston, <jjohnstn@redhat.com> wrote:

> Hello Harish,
>
> It isn't supported.  There are no top Makefile targets for you to do this
> and building targets directly from Makefiles in subdirectories often
> runs into issues (e.g. missing headers that haven't been copied or
> paths/vars set incorrectly since they are supposed to be set by parent
> Makefiles).
> In addition, the errno/reentrant mechanisms used by libm.a are supplied by
> libc.a.
>
> -- Jeff J.
>
> On Thu, Jul 15, 2021 at 7:44 AM Harish <harishcse44@gmail.com> wrote:
>
>> Hi newlib,
>>
>> I would like to build just libm.a library, is it possible? if yes, please
>> let me know how can I do it.
>>
>>
>> Thanks,
>> Harish C
>>
>>

Re: Building libm library

[Jeff Johnston]

On Thu, Jul 15, 2021 at 8:54 PM Harish <harishcse44@gmail.com> wrote:

> Ok, thanks for the clarification. One more question. I would like to use
> math library on a baremetal and want to know if the newlib math library
> uses system calls?. If yes, is there any other implementation which can be
> used for baremetals?
>
>
libm does not call system calls.  If you want to implement libc but don't
want to implement system calls, you can use libnosys which is a stub
library (e.g. reads fail, writes fail, etc...).
It is built as part of libgloss and you simply reference it using -lnosys
in your link.

Regards,
> Harish
>
> On Thu, 15 Jul, 2021, 11:19 pm Jeff Johnston, <jjohnstn@redhat.com> wrote:
>
>> Hello Harish,
>>
>> It isn't supported.  There are no top Makefile targets for you to do this
>> and building targets directly from Makefiles in subdirectories often
>> runs into issues (e.g. missing headers that haven't been copied or
>> paths/vars set incorrectly since they are supposed to be set by parent
>> Makefiles).
>> In addition, the errno/reentrant mechanisms used by libm.a are supplied
>> by libc.a.
>>
>> -- Jeff J.
>>
>> On Thu, Jul 15, 2021 at 7:44 AM Harish <harishcse44@gmail.com> wrote:
>>
>>> Hi newlib,
>>>
>>> I would like to build just libm.a library, is it possible? if yes, please
>>> let me know how can I do it.
>>>
>>>
>>> Thanks,
>>> Harish C
>>>
>>>

Re: Building libm library

[Harish]

Got it, Thank you :)

On Fri, Jul 16, 2021 at 9:16 AM Jeff Johnston <jjohnstn@redhat.com> wrote:

>
>
> On Thu, Jul 15, 2021 at 8:54 PM Harish <harishcse44@gmail.com> wrote:
>
>> Ok, thanks for the clarification. One more question. I would like to use
>> math library on a baremetal and want to know if the newlib math library
>> uses system calls?. If yes, is there any other implementation which can be
>> used for baremetals?
>>
>>
> libm does not call system calls.  If you want to implement libc but don't
> want to implement system calls, you can use libnosys which is a stub
> library (e.g. reads fail, writes fail, etc...).
> It is built as part of libgloss and you simply reference it using -lnosys
> in your link.
>
> Regards,
>> Harish
>>
>> On Thu, 15 Jul, 2021, 11:19 pm Jeff Johnston, <jjohnstn@redhat.com>
>> wrote:
>>
>>> Hello Harish,
>>>
>>> It isn't supported.  There are no top Makefile targets for you to do
>>> this and building targets directly from Makefiles in subdirectories often
>>> runs into issues (e.g. missing headers that haven't been copied or
>>> paths/vars set incorrectly since they are supposed to be set by parent
>>> Makefiles).
>>> In addition, the errno/reentrant mechanisms used by libm.a are supplied
>>> by libc.a.
>>>
>>> -- Jeff J.
>>>
>>> On Thu, Jul 15, 2021 at 7:44 AM Harish <harishcse44@gmail.com> wrote:
>>>
>>>> Hi newlib,
>>>>
>>>> I would like to build just libm.a library, is it possible? if yes,
>>>> please
>>>> let me know how can I do it.
>>>>
>>>>
>>>> Thanks,
>>>> Harish C
>>>>
>>>>

Re: Building libm library

[Paul Zimmermann]

       Hi Harish,

> I would like to build just libm.a library, is it possible? if yes, please
> let me know how can I do it.

I don't know if this answers your question, but here is how I compile Newlib
libm.a on x86_64 under Linux:

tar xf newlib-4.1.0.tar.gz
cd newlib-4.1.0
mkdir build
cd build
../configure --prefix=/tmp --target=x86_64 --disable-multilib
make -j4

Best regards,
Paul

Re: Building libm library

[Harish]

Thanks, Paul. I'm able to build Newlib.

On Mon, Jul 19, 2021 at 1:49 PM Paul Zimmermann <Paul.Zimmermann@inria.fr>
wrote:

>        Hi Harish,
>
> > I would like to build just libm.a library, is it possible? if yes, please
> > let me know how can I do it.
>
> I don't know if this answers your question, but here is how I compile
> Newlib
> libm.a on x86_64 under Linux:
>
> tar xf newlib-4.1.0.tar.gz
> cd newlib-4.1.0
> mkdir build
> cd build
> ../configure --prefix=/tmp --target=x86_64 --disable-multilib
> make -j4
>
> Best regards,
> Paul
>