New Build System Status

[Sebastian Huber]

On 01/12/2019 23:53, Chris Johns wrote:
> On 27/11/19 11:26 pm, Sebastian Huber wrote:
>> On 27/11/2019 13:17, Hesham Almatary wrote:
>>> On Wed, 27 Nov 2019 at 11:59, Sebastian Huber
>>> <sebastian.huber at embedded-brains.de> wrote:
>>>> On 27/11/2019 12:49, Hesham Almatary wrote:
>>>>> Hi Sebastian,
>>>>>
>>>>> Thanks for that great effort. I'd aim to use this build system for my
>>>>> RISC-V development.
>>>>>
>>>>> I followed the user manual trying to build RISC-V targets and RTEMS
>>>>> (aaf7f8b84) and here are a few comments:
>>>>>
>>>>> * .waf bsp_defaults doesn't give an error when mistyping the BSP name,
>>>>> but just outputs an empty .ini file.
>>>>
>>>> If there is no matching BSP, then you get nothing. I think this is the
>>>> right thing to do.
> 
> If the user does not enter the correct BSP name we should provide an relevant
> error message on stderr and return a non-zero error code. I believe we should
> not silently move past an error without a clear indication there is a problem.

We are talking here about the "./waf bsp_defaults" command. I think it 
is perfectly fine to output nothing if there is nothing to output. This 
is the normal UNIX style. What happens if you grep for something which 
doesn't exits? Anyway, I changed the command like this:

$ ./waf bsp_defaults --rtems-specs=spec/build/cpukit
# The build specification contains no BSPs

$ ./waf bsp_defaults --rtems-bsps=foobar,perfection
# No BSP matches with the specified patterns: 'foobar', 'perfection'

> 
>>>> Doing a
>>>>
>>>> ./waf bsp_defaults --rtems-bsps=riscv/rv64imac_medany  > bsps.ini
>>>>
>>>> is not a recommended use case. You should only set the necessary minimum
>>>> of options.
> 
> If this documented?

Yes, but apparently not good enough. I will try to fix this.

> 
>>> Not sure, I only wanted to build a specific BSP variant without having
>>> to build all variants. Is that not recommended?
>>
>> This is fine, but I would not dump all options into the config.ini, maybe just:
>>
>> [riscv/rv64imac_medany]
>> COMPILER = clang
>> BUILD_TESTS = True
> 
> How do you get a list of valid options and values to know what to set and not set?

You get the options with default values via "./waf bsp_defaults". You 
should only set options for which you don't like the default value. For 
example, some BSPs allow you to set the initial value of some registers, 
e.g.

# initial BUCSR value
QORIQ_INITIAL_BUCSR = 0x01400201

Lets suppose a chip errata appears and it says you have to set the 
undocumented bit 31 to activate an errata workaround. You change the 
value in the build specification to 0x81400201 in the RTEMS sources. 
Everyone who did a

./waf bsp_defaults --rtems-bsps=xxx  > config.ini

will not profit from this bug fix.

> 
> If you do not providing a value do you get your current version's default? Does
> this make updating defaults in rtems.git more complicated?
> 
>>>>> * ./waf complains about not finding gcc if I don't give it the
>>>>> --prefix, even though it's in my PATH
>>>>
>>>> Yes, this is currently the intentional behaviour. Should this be changed to
>>>>
>>>> conf.find_program(XYZ, path_list=tools +
>>>> environ.get('PATH','').split(os.pathsep))
>>>>
>>>> ?
>>> I think that makes sense (also for default prefix?), but it would
>>> still be useful to be able to override that with --prefix to use
>>> different installed toolchains if needed.
>>
>> Chris, what is your opinion on this?
> 
> A rigorous approach would ignore a user's path because paths are something we
> are not good at maintaining and this can lead to subtle issues in a project that
> are hard to figure out.
> 
> The rtems_waf behavior currently is:
> 
> 1. --rtems-tools is the first path searched
> 2. --prefix if no --rtems-tools
> 3. $PATH if no --rtems-tools and no --prefix
> 
> I am fine with rtems.git's waf doing the same thing.

Ok, I changed it like this:

def get_path_list(conf):
     path_list = []
     tools = conf.options.rtems_tools
     if tools is not None:
         for t in tools.split(","):
             path_list.extend([t + "/bin", t])
     path_list.append(conf.env.PREFIX + "/bin")
     path_list.extend(os.environ.get("PATH", "").split(os.pathsep))
     return path_list

-- 
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber at embedded-brains.de
PGP     : Public key available on request.

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