RPi3b, U-Boot, EFI and Serial Input

[Anthony Davies]

Hi,

I am running mainline grub built from source. Are you using it successfully
on Raspberry Pi 3b or another SBC?

At this stage my testing is as follows all using the exact same firmware,
kernel and ramdisk:
- u-boot -> kernel+ramdisk - No input
- u-boot -> grub/ipxe -> kernel+ramdisk - No input to the efi or linux once
booted
- pixpe (sdcard with firmware, edk2 and ipxe.efi) - Input works
- firmware -> kernel+ramdisk - Input works

The only common component that seems to stop the input working is u-boot
once it has booted into something else as it works fine on the u-boot
command line.

I did as you suggested and used a script to boot all the way to a linux
shell but unfortunately I still can't provide input via serial.

I have the exact same setup on other SBCs (lime2 and Rock Pi 4) though
obviously slightly different kernels and I dont experience the same issue,
it seems localised to Raspberry Pi. I cant test other Pi boards as I only
own the 3B.

My only assumption is I am missing something in my u-boot compile config
but I have no idea what that would be, all the appropriate drivers seem to
be there and functioning within u-boot itself, just post is an issue.

Cheers

On Sun, 18 Oct 2020 at 22:38, Michal Suchánek <msuchanek at suse.de> wrote:

> Hello,
>
> On Sun, Oct 18, 2020 at 09:40:00PM +1100, Anthony Davies wrote:
> > Hi All,
> >
> > I am having an issue where it seems after u-boot has booted an EFI it
> > doesnt seem to "release" the serial console input.
> >
> > I have had this happen using the iPXE efi similar to
> > https://lists.denx.de/pipermail/u-boot/2018-April/324802.html and also
> when
> > using the grub efi.
> In grub efi the console works for me but there is no single 'grub' -
> each distribution adds a number of patches on top.


> Also I would expect that grub and iPXE running as EFI binary would use
> console through EFI calls and then u-boot should not 'release' the
> console - it should continue to provide the EFI service to grub and iPXE.
>
> There is an option to include a boot script in iPXE. If that is
> preserved when built as EFI binary you can test other iPXE features
> without typing on the console.
>
> Thanks
>
> Michal
>