Re: [4.3-rc1 regression] modular 8250 doesn't load

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Sep 14, 2015 at 10:42:24PM +0200, Mikael Pettersson wrote:
> Greg Kroah-Hartman writes:
>  > On Mon, Sep 14, 2015 at 08:06:21PM +0200, Mikael Pettersson wrote:
>  > > Greg Kroah-Hartman writes:
>  > >  > On Mon, Sep 14, 2015 at 07:08:10PM +0200, Mikael Pettersson wrote:
>  > >  > > I have CONFIG_SERIAL_8250=m.  With 4.2 '/sbin/modprobe 8250' worked
>  > >  > > and resulted in:
>  > >  > > 
>  > >  > > [   41.354550] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
>  > >  > > [   41.375156] serial8250: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
>  > >  > > 
>  > >  > > With 4.3-rc1 however the command fails and logs the following:
>  > >  > > 
>  > >  > > [   34.140300] 8250_base: module license 'unspecified' taints kernel.
>  > >  > 
>  > >  > Oops, need to fix that.
>  > >  > 
>  > >  > > [   34.141846] Disabling lock debugging due to kernel taint
>  > >  > > [   34.143388] 8250_base: Unknown symbol uart_insert_char (err 0)
>  > >  > > [   34.144908] 8250_base: Unknown symbol uart_handle_dcd_change (err 0)
>  > >  > > [   34.146439] 8250_base: Unknown symbol __pm_runtime_resume (err 0)
>  > >  > > [   34.147901] 8250_base: Unknown symbol tty_termios_encode_baud_rate (err 0)
>  > >  > > [   34.149354] 8250_base: Unknown symbol uart_handle_cts_change (err 0)
>  > >  > > [   34.150798] 8250_base: Unknown symbol __pm_runtime_suspend (err 0)
>  > >  > > [   34.152240] 8250_base: Unknown symbol nr_irqs (err 0)
>  > >  > 
>  > >  > Are you sure you did 'modprobe' and not 'insmod'?
>  > > 
>  > > Yes, I used modprobe.  I double-checked.
>  > 
>  > Then your build should have failed if these functions are not being
>  > exported properly by your .config.  Most of these are in the serial_core
>  > module, is that present/loaded?
> 
> Yes, serial_core is loaded.
> 
> uart_insert_char is EXPORT_SYMBOL_GPL, so could the missing license tag be preventing
> 8250_core from binding to it?  (I haven't checked the other symbols but I assume they
> are also _GPL.)

Ah, crap, yes, you are right.  You can test this with a simple:
	MODULE_LICENSE("GPL");
line added to the 8250_base file.

thanks,

greg k-h