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<p><font color="#3333ff"><font color="#000000">Comments inline:</font></font></p>
<p><font color="#3333ff"><font color="#000000">...<br>
</font></font></p>
<blockquote type="cite" cite="mid:0310a376-1e04-5e53-73f2-a95cd774eace@windriver.com">For
centos, we found that loops almost always depend on one of a
handful of low level packages, e.g. bash, python, gcc, rpm <br>
<blockquote type="cite" cite="mid:91aa695a-9ef2-3945-7a73-542cd3838db8@windriver.com">
<blockquote type="cite"> <br>
We had two ways to try and deal with this. <br>
<br>
1) Allow the use of a pre-compiled binary from upstream to
satisfy the dependency when the StarlingX modification are
unlikely to affect how dependent packages compile. Packages
in the 'mock' lst files could satisfy this type of
requirement. <br>
e.g. A=bash <br>
So in your example, compile order would be: <br>
F (vs upstream A), D (vs upstream A), C, B, A <br>
<br>
2) Use a different 'build-type'... other than 'std' or 'rt'
... when the modified StarlingX package was likely to affect
the output of dependent packages. Compile packages in that
build type first. <br>
e.g. A=rpm <br>
= build-type 'installer' compile order would be: <br>
A (vs upstream binaries) B and C ... call this
A-intermediate <br>
</blockquote>
? So, the 'installer' type of A doesn't depend on B and C,
right? Just like the official method to break the loop manually?
<br>
</blockquote>
<p><font color="#3333ff">[SL] I wouldn't say that A doesn't depend
on B or C. Rather the 'installer' package set does not build
B or C, so they do not factor into build order calculations.
This does require that upstream B and C be available to
satisfy build dependencies when compiling within the
'installer' package set. When compiling the 'std' set, but the
packages from the 'installer' package must be available to
satisfy dependencies. The 'installer' compiled versions of B
and C must be of higher version that those from upstream...
and thus installed instead of the upstream ones.</font></p>
</blockquote>
<p><font color="#400040">So? In this kind of case, we also needn't
break the loop manually but just separate the into different
layers/sets and compile them in different stage, right?</font></p>
<p><font color="#400040">In the bottom logic(or, with the compiler's
point of view), it is the same with the first one. The key
difference comes from the special package A. It's so basic that
it has to be compiled tice<br>
</font></p>
<blockquote type="cite" cite="mid:0310a376-1e04-5e53-73f2-a95cd774eace@windriver.com">
<blockquote type="cite" cite="mid:91aa695a-9ef2-3945-7a73-542cd3838db8@windriver.com">
<blockquote type="cite"> = build-type 'std' compile order would
be: <br>
F (vs A-intermediate), D (vs A-intermediate), C, B, A
<br>
<br>
</blockquote>
Seems the first one is more fit for automatic build. Then, any
special cases thus we have to use the second method? Or we can
always use the first one? <br>
<br>
</blockquote>
<p><font color="#3333ff">[SL] You'll need to support both methods
of resolving dependency cycles. <br>
</font></p>
<p><font color="#3333ff">Note that the layered build concept of
the CentOS build was another way to address partitioning of
packages into sets that might help with breaking dependency
loops by not having A,B,C in the same compile set. Look to the
'compiler' layer. <br>
</font></p>
<p><font color="#3333ff">I think you need to support at least one
of the 'build-type' or 'build layer' concepts to begin with.
Bonus points if you support both. Supporting both was needed
for the 'rpm' package which we wanted to patch, and the patch
does alter the format of the rpms generated, and the rpm
package itself had to be in that format. So rpm was compiled
for build-type 'installer' of layer 'compiler' (new rpm code
in old rpm package), then recompiled in build-type 'std' of
layer </font><font color="#3333ff">'compiler' (new rpm code
in new rpm package). Finally the std build of rpm was
published for use by higher layer builds.<br>
</font></p>
<p><font color="#3333ff">Only designers working on packages in the
'installer' set, or the 'compiler' layer, need to worry about
the multi pass build. For most packages, a single pass
'flock' layer, 'std' build-type, build is fine.</font></p>
</blockquote>
<p>So, in build process, we need to build "compiler" layer firstly,
then use the new build "compilers" build other layers. Some
special packages like "rpm" may exist in more than one
layers/sets.</p>
<p><br>
</p>
<p>BTW: I suppose the upstream rpm is already powerful enough, why
we have to modify it? Just bug fix or new features? If the later
one, StarlingX need some special features it hasn't? It maybe very
useful/important for us in porting StarlingX onto other Linux
releases.<br>
</p>
<p><br>
</p>
<p>Thanks</p>
<p>Xiao<br>
</p>
<p><br>
</p>
<blockquote type="cite" cite="mid:0310a376-1e04-5e53-73f2-a95cd774eace@windriver.com">
<p><font color="#3333ff">Scott</font></p>
<p><font color="#3333ff"><br>
</font></p>
<blockquote type="cite" cite="mid:91aa695a-9ef2-3945-7a73-542cd3838db8@windriver.com"> <br>
Thanks <br>
<br>
Xiao <br>
<br>
<blockquote type="cite">Scott <br>
<br>
<br>
On 2021-09-18 2:50 a.m., Zhang, Xiao wrote: <br>
<blockquote type="cite"> Hi， <br>
<br>
<br>
We are trying to construct basic environment for porting
starlingX on Debian. While when I dealing with the build
order of user space packages, the loop dependent problem
blocked me. <br>
<br>
The easiest example: source package A build depend on B
while B is also build depend on A. We can just build A, B,
A, B and only use the later result. <br>
<br>
A fairly complex example: A depends on B and C, B depends on
D, C depends on F, D depends on A and F. In this case there
will be three cycles as below: <br>
<br>
A->B->D->A, A->B->D->F->A,
A->C->F->A . Even more, if in some cases we needn't
B or D, then we have only one cycle: ACFA <br>
<br>
I tried to find a method to deal with it but failed. <br>
<br>
So I wonder how did we deal with such loop dependent before,
on CentOS. Any advises about it? <br>
<br>
<br>
Thanks a lot <br>
<br>
Xiao <br>
<br>
<br>
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