PackagingDrafts/ArchSpecificRequires

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(When To Do It)
(Making Requires Arch-Specific)
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== Making Requires Arch-Specific ==
 
== Making Requires Arch-Specific ==
Requires can be made arch-specific by appending the macro <code>%{?_isa}</code> to the package name.  For instance,
+
Explicit requires must be made arch-specific by appending the macro <code>%{?_isa}</code> to the package name.  For instance,
  
 
  Requires: foo
 
  Requires: foo

Revision as of 13:44, 10 May 2010

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This page is a draft only
It is still under construction and content may change. Do not rely on the information on this page.

Rationale

rpm/yum treat a dependency (Requires) on “foo” as satisfiable by any available foo, regardless of architecture. The consequence of this is that on multilib systems, when the architecture of a dependency has not been specified (even though it is important), yum can install the wrong architecture build of the dependency—resulting in, most likely, a nonfunctional installation. This appears to happen when, for some reason, the correct architecture is not available to yum.

Making Requires Arch-Specific

Explicit requires must be made arch-specific by appending the macro %{?_isa} to the package name. For instance,

Requires: foo

becomes

Requires: foo%{?_isa}

When To Do It

If a dependency really can be satisfied by a build for any architecture, clearly there's no reason to make the dependency architecture-specific. But it does matter in these scenarios:

  • A library in the dependency is dlopen'd.
  • A non-noarch -devel package depends on another -devel package.
  • A non-noarch subpackage's dependency on its main package.

So, unless you have a very good reason to not make an explicit dependency architecture specific, you MUST do it.