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

From: Greg Kroah-Hartman
Date: Mon Sep 14 2015 - 14:50:58 EST


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?

thanks,

greg k-h
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