On Tue, 2008-03-25 at 11:56 -0400, Jerry Van Baren wrote: > Joakim Tjernlund wrote: > > On Tue, 2008-03-25 at 10:57 -0400, Ben Warren wrote: > >> Joakim Tjernlund wrote: > >>> On Tue, 2008-03-25 at 10:22 -0400, Ben Warren wrote: > >>> > >>>> Stefan Roese wrote: > >>>> > >>>>> On Saturday 22 March 2008, Ben Warren wrote: > > [snip] > > >>>>> Using Markus's idea, why not use a cpu (platform) specific *and* a > >>>>> board > >>>>> specific init function, both with an empty weak alias in the common > >>>>> eth.c > >>>>> code: > >>>>> > >>>>> cpu_eth_init(bis); > >>>>> board_eth_init(bis); > >>>>> > >>>> I thought about this some more, and the problem is that cpu_eth_init() > >>>> and board_eth_init() > >>>> are mutually exclusive, with board_eth_init() having a higher priority. > >>>> I think the following will work, but would appreciate some feedback. > >>>> > >>>> ----- > >>>> > >>>> int board_eth_init(bd_t *bis) __attribute(weak); > >>>> int cpu_eth_init(bd_t *bis) __attribute(weak); > >>>> > >>>> . > >>>> . > >>>> . > >>>> > >>>> if (board_eth_init) > >>>> board_eth_init(bis); > >>>> else if (cpu_eth_init) > >>>> cpu_eth_init(bis); > >>>> > >>>> ----- > >>>> > >>>> This gets rid of the pointless aliases and gives precedence to the > >>>> board-specific initialization. > >>>> > >>>> > >>>> regards, > >>>> Ben > >>>> > >>> I think you must enable full relocation, CONFIG_RELOC_FIXUP_WORKS, to > >>> make the "if (board_eth_init)" work. This is just a guess though. > >>> > >>> Jocke > >>> > >>> > >> Nothing a little testing can't figure out. > >> > >> thanks, > >> Ben > > > > You could do too: > > if (!board_eth_init(bis)) > > cpu_eth_init(bis); > > > > Jocke > > Per an earlier discussion on how weak functions are implemented, these > are not equivalent. Functions marked "weak" *without* a weak > implementation become NULL pointers. The code > if (board_eth_init) > board_eth_init(bis); > else if (cpu_eth_init) > cpu_eth_init(bis); > uses that knowledge to see if the weak function board_eth_init() exists > and then calls it if it does. If it doesn't exist, it sees if > cpu_eth_init() exists and calls it if it does. > > Your counter proposal assumes that a weak function board_eth_init() > *does* exist and uses the returned result as the condition of executing > cpu_eth_init() (assuming it also exists). > > If you define a weak function that simply returns failure, your > alternative is close, but still not the same because an overridden > (*real*) board_eth_init() could return failure too, in which case it
Yes, see below for fix > > will (probably erroneously) execute cpu_eth_init(). Beyond that, if > cpu_eth_init() doesn't exist (doesn't have a default weak function > defined), the call to it will go *SPLAT*. > > HTH, > gvb > All true, I was thinking that there would be default weak dummy versions of both board_eth_init() and cpu_eth_init() that would do the right thing. To address the weakness you spotted one would need three return values, something like: -1 fail 0 not impl. 1 success Jocke ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ U-Boot-Users mailing list U-Boot-Users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/u-boot-users
