Re: [Xen-devel] [PATCH] golang/xenlight: Add libxl_utils support

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 7/19/19 11:03 AM, Nicolas Belouin wrote:
> 
> 
> On 7/19/19 10:50 AM, George Dunlap wrote:
>>
>>> On Jul 19, 2019, at 9:47 AM, George Dunlap <george.dunlap@xxxxxxxxxx> wrote:
>>>
>>>
>>>
>>>> On Jul 19, 2019, at 8:34 AM, Nicolas Belouin <nicolas.belouin@xxxxxxxxx> 
>>>> wrote:
>>>>
>>>>
>>>>
>>>> On 7/18/19 11:54 PM, George Dunlap wrote:
>>>>> The Go bindings for libxl miss functions from libxl_utils, let's start
>>>>> with the simple libxl_domid_to_name and its counterpart
>>>>> libxl_name_to_domid.
>>>>>
>>>>> NB that C.GoString() will return "" if it's passed a NULL; see
>>>>> https://github.com/golang/go/issues/32734#issuecomment-506835432
>>>>>
>>>>> Signed-off-by: Nicolas Belouin <nicolas.belouin@xxxxxxxxx>
>>>>> Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
>>>>> ---
>>>>> v3:
>>>>> - Wire into build system
>>>>> - Add reference to C.GoString() handling NULL to commit message
>>>>>
>>>>> Nicolas, could you test to see if this actually works for you?
>>>> Tested it, it works.
>>>>
>>>> I must confess I do not use that import path as the new modules mechanism
>>>> introduced in Go1.11 downloads and compile a versioned copy of every
>>>> dependency per project, and this behavior is incompatible with the build
>>>> system used here.
>>> It’s possible that something fundamentally has changed, but I suspect that 
>>> rather you don’t quite understand how the current build system is supposed 
>>> to work.  (In which case a write-up in the tree would probably be useful.)
>>>
>>> Go has always insisted that there be no binary compatibility between 
>>> versions; so it’s always been necessary to re-compile all your libraries 
>>> when upgrading from (say) 1.8 to 1.9.  Which means that any useable 
>>> distribution must also include all the source files necessary to recompile 
>>> when you bump the version number.
>>>
>>> So the core mechanism of the “install” is actually to copy all the source 
>>> files necessary into the right local directory such that the go compiler 
>>> can find them; ATM this is /usr/share/gocode/golang.xenproject.org/xenlight
>> Nit:  This of course should have a `src/` between `gocode/` and 
>> `golang.xenproject.org/`.
>>
>> NB also that this naming scheme was designed so that at some point in the 
>> future, we could actually host the xenlight packages at the URL provided.
>>
>>  -George
>>
> 
> This new mechanism of modules is described here:
> https://golang.org/cmd/go/#hdr-Modules__module_versions__and_more
> 
> The module system is intended to supersede the GOPATH approach and
> provide a way to get versioned dependencies, as such
> it does not rely on GOPATH at all and doesn't use sources or compiled
> packages present in GOPATH elements such as /usr/share/gocode
> and systematically fetch (at the asked version) and compile a copy of
> the dependency as it might be a different version from the one
> in GOPATH.
> 
> As far as I tried, I have been unable to build my module even with the
> library installed.
> I have to use xenbits.xen.org/git-http/xen.git/tools/golang/xenlight (or
> one of its mirror) in order to build the module using the new
> mechanism (the golang.xenproject.org/xenlight works when building with
> modules mode disabled).

I took a look at the module stuff when it came out, and I was never able
to make sense of how it was supposed to work.

<rant>On the whole, it seems they basically hate the idea of distro
packages, and seem intent on breaking them whenever people manage to
start to get them working.</rant>

 -George

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel