Public bug reported:
An upstream kernel change which was introduced to avoid high sub-level
numbers in 4.14.y to overflow into the minor number has uncovered a
similar issue with LTTNG's macros which allow versioned code adaptions.
To allow that the ABI number of the kernel is inserted as a new sub-
sub-level number. Which is done by shifting the existing
LINUX_VERSION_CODE by another 8 bits. But this only allows for ABI
numbers up to 255. After that they overflow into the sub-level part of
the kernel. This went unnoticed until the kernel side changed this
number to be 255 fix. Now the overflow reaches the minor number and this
breaks assumptions in the code.
For example bionic:linux-snapdragon (-1117) fails to produce lttng-
modules (DKMS) but the previous version would succeed. When changing the
LINUX_VERSION_CODE back, this works in both cases.
Since the macros are only used to make compile time decisions the
proposed fix would be to extend the ABI number size to 16bit. That will
work in all cases.
** Affects: lttng-modules (Ubuntu)
Importance: Undecided
Status: New
** Affects: lttng-modules (Ubuntu Bionic)
Importance: Medium
Assignee: Stefan Bader (smb)
Status: Triaged
** Also affects: lttng-modules (Ubuntu Bionic)
Importance: Undecided
Status: New
** Changed in: lttng-modules (Ubuntu Bionic)
Importance: Undecided => Medium
** Changed in: lttng-modules (Ubuntu Bionic)
Status: New => Triaged
** Changed in: lttng-modules (Ubuntu Bionic)
Assignee: (unassigned) => Stefan Bader (smb)
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https://bugs.launchpad.net/bugs/1953522
Title:
Ubuntu version macros overflow with high ABI numbers
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