Re: [PATCH v4 14/14] tty: gunyah: Add tty console driver for RM Console Services

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 10/7/2022 12:40 AM, Greg Kroah-Hartman wrote:
On Thu, Oct 06, 2022 at 10:59:51PM -0700, Elliot Berman wrote:

"GH" is the shorthand we've been using for "Gunyah". I didn't find
documentation for dynamically assigned char devices, but if it exists, I can
add entry for ttyGH.

Why use a new name at all?  Why not stick with the existing tty names
and device numbers?


I can use hvc framework, although driver-level buffering is needed on
both the get_chars/put_chars paths because:

 - get_chars wants to poll for characters, but Gunyah will push
   characters to Linux
 - put_chars can be called in atomic context in the printk console path.
   Gunyah RM calls can sleep, so we add to buffer and queue work to
   write the characters.

I also chose to use new tty driver because the Gunyah hypervisor call to open the console (gh_rm_console_open) can only be done after starting the VM. Gunyah will only forward characters sent from the other VM to Linux after the gh_rm_console_open call is made. When launching a VM, users would want to open console before VM starts so they can get startup messages from the VM. I planned to use the carrier_raised() to hold tty_port_block_until_ready until the VM is started and the gh_rm_console_open() happens.

Thanks,
Elliot



[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux