Public bug reported:

= SRU Justification =

Impact: Linking perf (part of the linux-tools package) against libbfd
prevents users to have linux-tools of different kernel versions
installed in parallel. Which makes debugging hard.

Fix: As stated above this had been fixed before but upstream changes of
the kernel between 4.19 and 5.0 voided those fixes. Unfortunately
without causing build failures but causing libbfd to be used again.

Testcase: Extracting ./usr/lib/linux-tools-*/perf from the generated
linux-tools package and inspecting it with ldd. Old builds will have a
reference to libbfd, the test builds will not.

Risk of regression: low as this is a build-time change.
=====

It seems the previous attempt to disable use of libbfd has been rendered
ineffective by an upstream change:

  commit 14541b1e7e723859ff2c75c6fc10cdbbec6b8c34
  Author: Stanislav Fomichev <s...@google.com>
  Date:   Thu Nov 15 16:32:01 2018 -0800

    perf build: Don't unconditionally link the libbfd feature test to
-liberty and -lz

This leads us to have a hard dependency on libbfd at a specific minor
version.  We do not need this library, we can use libiberty and others
for the same functions in perf.

This is a recurrance of Bug #1748922.

** Affects: linux (Ubuntu)
     Importance: High
         Status: Confirmed

** Affects: linux (Ubuntu Disco)
     Importance: High
     Assignee: Andy Whitcroft (apw)
         Status: Confirmed

** Affects: linux (Ubuntu Eoan)
     Importance: High
         Status: Confirmed

** Description changed:

  It seems the previous attempt to disable use of libbfd has been rendered
- ineffective by an upstream change.  This leads us to have a hard
- dependency on libbfd at a specific minor version.  We do not need this
- library, we can use libiberty and others for the same functions in perf.
+ ineffective by an upstream change:
+ 
+   commit 14541b1e7e723859ff2c75c6fc10cdbbec6b8c34
+   Author: Stanislav Fomichev <s...@google.com>
+   Date:   Thu Nov 15 16:32:01 2018 -0800
+ 
+     perf build: Don't unconditionally link the libbfd feature test to
+ -liberty and -lz
+ 
+ This leads us to have a hard dependency on libbfd at a specific minor
+ version.  We do not need this library, we can use libiberty and others
+ for the same functions in perf.
  
  This is a recurrance of Bug #1748922.

** Changed in: linux (Ubuntu)
       Status: New => Confirmed

** Changed in: linux (Ubuntu)
   Importance: Undecided => High

** Changed in: linux (Ubuntu)
     Assignee: (unassigned) => Andy Whitcroft (apw)

** Also affects: linux (Ubuntu Eoan)
   Importance: High
     Assignee: Andy Whitcroft (apw)
       Status: Confirmed

** Also affects: linux (Ubuntu Disco)
   Importance: Undecided
       Status: New

** Description changed:

+ = SRU Justification =
+ 
+ Impact: Linking perf (part of the linux-tools package) against libbfd
+ prevents users to have linux-tools of different kernel versions
+ installed in parallel. Which makes debugging hard.
+ 
+ Fix: As stated above this had been fixed before but upstream changes of
+ the kernel between 4.19 and 5.0 voided those fixes. Unfortunately
+ without causing build failures but causing libbfd to be used again.
+ 
+ Testcase: Extracting ./usr/lib/linux-tools-*/perf from the generated
+ linux-tools package and inspecting it with ldd. Old builds will have a
+ reference to libbfd, the test builds will not.
+ 
+ Risk of regression: low as this is a build-time change.
+ =====
+ 
  It seems the previous attempt to disable use of libbfd has been rendered
  ineffective by an upstream change:
  
-   commit 14541b1e7e723859ff2c75c6fc10cdbbec6b8c34
-   Author: Stanislav Fomichev <s...@google.com>
-   Date:   Thu Nov 15 16:32:01 2018 -0800
+   commit 14541b1e7e723859ff2c75c6fc10cdbbec6b8c34
+   Author: Stanislav Fomichev <s...@google.com>
+   Date:   Thu Nov 15 16:32:01 2018 -0800
  
-     perf build: Don't unconditionally link the libbfd feature test to
+     perf build: Don't unconditionally link the libbfd feature test to
  -liberty and -lz
  
  This leads us to have a hard dependency on libbfd at a specific minor
  version.  We do not need this library, we can use libiberty and others
  for the same functions in perf.
  
  This is a recurrance of Bug #1748922.

** Changed in: linux (Ubuntu Disco)
       Status: New => Confirmed

** Changed in: linux (Ubuntu Disco)
   Importance: Undecided => High

** Changed in: linux (Ubuntu Disco)
     Assignee: (unassigned) => Andy Whitcroft (apw)

** Changed in: linux (Ubuntu Eoan)
     Assignee: Andy Whitcroft (apw) => (unassigned)

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https://bugs.launchpad.net/bugs/1828234

Title:
   linux-tools: perf incorrectly linking libbfd -- again

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