On 06/25/20 15:51, Ard Biesheuvel wrote: > On 6/24/20 3:34 PM, Sami Mujawar wrote: >> The BaseSerialPortLib16550 library does not implement >> a constructor. This prevents the correct constructor >> invocation order for dependent libraries. >> e.g. A PlatformHookLib (for the Serial Port) may have >> a dependency on retrieving data from a Hob. A Hob >> library implementation may configure its initial state >> in the HobLib constructor. Since BaseSerialPortLib16550 >> does not implement a constructor, the Basetools do not >> resolve the correct order for constructor invocation. >> >> To fix this, add an empty constructor to the serial port >> library BaseSerialPortLib16550. >> >> Signed-off-by: Sami Mujawar <sami.muja...@arm.com> > > Acked-by: Ard Biesheuvel <ard.biesheu...@arm.com> > > Note to maintainers: > this works around a long standing BaseTools bug where constructor > dependencies do not propagate through a library that lacks a constructor. > > For instance, in the following case > > LibA depends on LibB depends on LibC > > the constructors are *only* guaranteed to be invoked in the correct > order (LibC, then LibB, then LibA) if LibB has a constructor in the > first place, otherwise, the remaining constructors for LibA and LibC > could be emitted in any order.
By now I've flipped my "mental default" to "use a constructor *unless* counter-indicated by something"... If we get a cycle due to always using constructors, the tools at least complain (and we know something's fishy). With the opposite default, I simply cannot guarantee that my new library instance LibB will *never* break an eventual LibA -> LibB -> LibC constructor dependency chain. In my new lib instance, I'm of course aware of the LibB -> LibC dependency, but I can't tell anything about a future LibA -> LibB dependency. :( So I guess it's prudent to always add a constructor, even if it's empty. Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#61743): https://edk2.groups.io/g/devel/message/61743 Mute This Topic: https://groups.io/mt/75081484/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
