| Message ID | 20230513055804.23775-1-rdunlap@infradead.org (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | [RFC] powerpc: udbg: export udbg_putc | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 24 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 6 jobs. |
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 <rdunlap@infradead.org> > Cc: Michael Ellerman <mpe@ellerman.id.au> > Cc: Nicholas Piggin <npiggin@gmail.com> > Cc: Christophe Leroy <christophe.leroy@csgroup.eu> > Cc: linuxppc-dev@lists.ozlabs.org > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: "Pali Rohár" <pali@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 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. Any other opinion?
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 <rdunlap@infradead.org> >> Cc: Michael Ellerman <mpe@ellerman.id.au> >> Cc: Nicholas Piggin <npiggin@gmail.com> >> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> >> Cc: linuxppc-dev@lists.ozlabs.org >> Cc: Arnd Bergmann <arnd@arndb.de> >> Cc: "Pali Rohár" <pali@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. > Any other opinion? Yes, please. Otherwise I prefer my option 2.
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 <rdunlap@infradead.org> > >> Cc: Michael Ellerman <mpe@ellerman.id.au> > >> Cc: Nicholas Piggin <npiggin@gmail.com> > >> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> > >> Cc: linuxppc-dev@lists.ozlabs.org > >> Cc: Arnd Bergmann <arnd@arndb.de> > >> Cc: "Pali Rohár" <pali@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.
On 5/13/23 16:05, Pali Rohár wrote: > 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 <rdunlap@infradead.org> >>>> Cc: Michael Ellerman <mpe@ellerman.id.au> >>>> Cc: Nicholas Piggin <npiggin@gmail.com> >>>> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> >>>> Cc: linuxppc-dev@lists.ozlabs.org >>>> Cc: Arnd Bergmann <arnd@arndb.de> >>>> Cc: "Pali Rohár" <pali@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? No, it just prevents SERIAL_CPM_CONSOLE from being set when SERIAL_CPM=m. >>> Any other opinion? >> >> Yes, please. Otherwise I prefer my option 2. >> >> -- >> ~Randy > > Option 2 looks like a better solution. Thanks.
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);
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 <rdunlap@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: linuxppc-dev@lists.ozlabs.org Cc: Arnd Bergmann <arnd@arndb.de> Cc: "Pali Rohár" <pali@kernel.org> --- arch/powerpc/kernel/udbg.c | 1 + 1 file changed, 1 insertion(+)