On Saturday 13 May 2023 15:53:19 Randy Dunlap wrote: > Hi Pali, > > On 5/13/23 02:13, Pali Rohár wrote: > > On Friday 12 May 2023 22:58:04 Randy Dunlap wrote: > >> In a randconfig with CONFIG_SERIAL_CPM=m and > >> CONFIG_PPC_EARLY_DEBUG_CPM=y, there is a build error: > >> ERROR: modpost: "udbg_putc" [drivers/tty/serial/cpm_uart/cpm_uart.ko] > >> undefined! > >> > >> The build can be fixed by exporting "udbg_putc" in udbg.c. > >> > >> OTOH, maybe something like this is more appropriate in > >> arch/powerpc/Kconfig.debug? > >> > >> config PPC_EARLY_DEBUG_CPM > >> bool "Early serial debugging for Freescale CPM-based serial ports" > >> - depends on SERIAL_CPM > >> + depends on SERIAL_CPM=y > >> > >> Signed-off-by: Randy Dunlap <rdun...@infradead.org> > >> Cc: Michael Ellerman <m...@ellerman.id.au> > >> Cc: Nicholas Piggin <npig...@gmail.com> > >> Cc: Christophe Leroy <christophe.le...@csgroup.eu> > >> Cc: linuxppc-dev@lists.ozlabs.org > >> Cc: Arnd Bergmann <a...@arndb.de> > >> Cc: "Pali Rohár" <p...@kernel.org> > >> --- > >> arch/powerpc/kernel/udbg.c | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff -- a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c > >> --- a/arch/powerpc/kernel/udbg.c > >> +++ b/arch/powerpc/kernel/udbg.c > >> @@ -14,6 +14,7 @@ > >> #include <asm/udbg.h> > >> > >> void (*udbg_putc)(char c); > >> +EXPORT_SYMBOL(udbg_putc); > >> void (*udbg_flush)(void); > >> int (*udbg_getc)(void); > >> int (*udbg_getc_poll)(void); > > > > Hello! I do not think that it is a good idea to export udbg functions > > for kernel modules. I have quickly looked at the cpm_uart driver file > > Sure, that was just a conversation starter. > > > drivers/tty/serial/cpm_uart/cpm_uart_core.c and it looks like that once > > udbg from it is registered then there is no code for unregistering it. > > So I have feeling that compiling cpm_uart driver as module should not be > > allowed when CONFIG_SERIAL_CPM_CONSOLE is enabled, and early debug > > should depend on CONFIG_CONSOLE_POLL || CONFIG_SERIAL_CPM_CONSOLE. > > The other change above also fixes the build error: (Option 2) > > >> config PPC_EARLY_DEBUG_CPM > >> bool "Early serial debugging for Freescale CPM-based serial ports" > >> - depends on SERIAL_CPM > >> + depends on SERIAL_CPM=y > > > Also, making SERIAL_CPM (cpm_uart driver) be restricted to not allow it > as a module when SERIAL_CPM_CONSOLE is enabled [how does one express that > in Kconfig language?] will cause a circular dependency since > SERIAL_CPM_CONSOLE > depends on SERIAL_CPM=y. It looks like you are suggesting reversing the > dependencies.
I see that SERIAL_CPM_CONSOLE has already "depends on SERIAL_CPM=y". Am I right that this already disallow compiling cpm_uart driver as module when SERIAL_CPM_CONSOLE is enabled? > > Any other opinion? > > Yes, please. Otherwise I prefer my option 2. > > -- > ~Randy Option 2 looks like a better solution.
