Re: Hi, how can I compile udev with cross compilation?

[Dan Nicholson <dbn.lists@gmail.com>]

On Sat, Feb 20, 2010 at 11:15 AM, Paul Bender <pebender@san.rr.com> wrote:
> On 2/20/2010 10:20 AM, Dan Nicholson wrote:
>>
>> On Sat, Feb 20, 2010 at 8:37 AM, Paul Bender<pebender@san.rr.com>  wrote:
>>>
>>> On 2/20/2010 1:52 AM, huyle wrote:
>>>>
>>>> Hi,
>>>> I am currently building an linux system for arm board. I am stuck with
>>>> udev. So can you help me with some commands to compile udev with cross
>>>> compilation?
>>>> Thanks for your time
>>>
>>> I am cross compiling udev, but not for the ARM.
>>>
>>> The only trouble that I have encountered when cross compiling version 151
>>> is
>>> with the configure scripts determination of the pci.ids file location.
>>> This
>>> is caused by autoconf's AC_CHECK_FILES macro generating an error when
>>> cross
>>> compiling. However, this can be worked around by setting
>>>
>>> ac_cv_file__usr_share_pci_ids='no'
>>> ac_cv_file__usr_share_hwdata_pci_ids='no'
>>> ac_cv_file__usr_share_misc_pci_ids='no'
>>>
>>> in the build system's environment before running configure and setting
>>> the
>>> configure script's --with-pci-ids-path argument.
>>>
>>> I have had this work around for so long that I have not given it much
>>> thought. However, it is relatively easy to fix the configure script so
>>> that
>>> it only attempting to determine the pci.ids file location when
>>> --with-pci-ids-path is not set. Therefore, I have created and attached a
>>> patch that should do this. Of course, after applying, you would need to
>>> rerun autoconf or autoreconf.
>>
>> I think it would be better to just make the AC_CHECK_FILES conditional
>> on cross compiling:
>>
>> if test $cross_compiling != yes; then
>>     AC_CHECK_FILES...pci.ids not found, try --with-pci-ids-path
>> else
>>     # just assume pciids location
>>     pciids=/usr/share/pci.ids
>> fi
>>
>> Otherwise, people cross compiling will bomb unless they pass
>> --with-pci-ids-path.
>
> Unless I misunderstand AC_ARG_WITH, its third argument is for what to do
> when the corresponding --with configure argument is not provided, which is
> how it behaves in my build system (with autoconf 2.63). That is why I put
> the AC_CHECK_FILES in the third argument.
>
> I like your patch better than mine as it does not generate the unhelpful
> error message:
> "cannot check for file existence when cross compiling".
> when the --with-pci-ids-path is not provided.
>
> However, for cross compiling, it might be better to force the user to
> provide --with-pci-ids-path rather than assuming one since an incorrect
> assumed path would not be discovered until on target runtime.

Yeah, there's definitely a balance there. That's why I added the
message so people would at least see what udev was going to use. I
just prefer the "don't make people pass options to configure unless
they definitely have to" approach. Could easily go both ways, though.

>> Likewise, you changed the 'test -n "$pciids"' to
>> a 'test -x'. I don't know a lot of people with an executable pci
>> database. Attached is a patch to do this.
>
> Doh, that was supposed to be -z. Thanks for the catch.

With that fix I think either patch would be fine.

--
Dan