Status of kernel

John G. Heim jheim at math.wisc.edu
Sun Nov 13 17:05:53 EST 2016


One thing I've never understood is why the kernel can have a serial 
console yet speakup can't talk to the serial port. How does the kernel's 
serial console talk to the serial port? Why can't speakup do the same?




On 11/12/2016 04:18 PM, Samuel Thibault wrote:
> Okash Khawaja, on Sat 12 Nov 2016 16:13:22 +0000, wrote:
>> Could you explain your idea a bit more? I have been reading the driver code and
>> want to contribute to this project.
> Just copy/pasting some previous thoughts. The idea would be to make
> speakup a tty line discipline, just like it is for a mouse, ppp, etc.
>
>> land? One of the goals of speakup is to be available before userland
> works (otherwise we could as well just move the drivers to userland), so
> we don't have any userland helper to set the line disciline up.
>
> And even before setting up the line discipline, how can speakup open
> the port?  We don't have a process context or /dev/, so we can't just
> use sys_open and alike.  What we could use is some function which takes
> a minor/major pair or a device name, and returns a filp, then we can
> tty_set_ldisc(N_SPEAKUP) on file_tty(filp), but I don't know if such
> thing exists?  That would probably be building a struct inode (getting
> inspired from fs/ramfs/), then just open it? Something like:
>
> struct inode *inode = new_inode(sb);
>
> init_special_inode(inode, S_IFCHR, MKDEV(major, minor));
> filp = get_empty_filp();
> do_dentry_open(filp, inode, NULL, NULL);
> struct tty_struct *tty = file_tty(filp);
> tty_set_ldisc(tty, N_SPEAKUP);
>>
> Samuel
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