[U-Boot] EFI_PXE_BASE_CODE_PROTOCOL

[Heinrich Schuchardt]

Hello Leif,

iPXE uses the EFI simple network protocol to execute DHCP.

Can GRUB already do the same when the EFI_PXE_BASE_CODE_PROTOCOL is not
present?

What I do not understand about GRUB's grub_net_configure_by_dhcp_ack()
is that it silently assumes IPv4 being used without even checking. This
contradicts the definition of the PXE base code protocol in the UEFI
standard:

EFI_PXE_BASE_CODE_PACKET DhcpAck is a union:

typedef union {
  UINT8                             Raw[1472];
  EFI_PXE_BASE_CODE_DHCPV4_PACKET   Dhcpv4;
  EFI_PXE_BASE_CODE_DHCPV6_PACKET   Dhcpv6;
} EFI_PXE_BASE_CODE_PACKET;

Should the check be done in grub_efi_net_config_real()?

Best regards

Heinrich

On 8/5/19 10:08 PM, Heinrich Schuchardt wrote:
> Hello Alex,
>
> lib/efi_loader/efi_net.c contains pieces of the
> EFI_PXE_BASE_CODE_PROTOCOL. But it is incompletely implemented: all
> function pointers are NULL and so immediate failure is expected when
> using the protocol.
>
> Do you remember why you introduced this protocol into U-Boot?
> It is not part of the EBBR specification.
>
> It is not needed for booting via GRUB from disk but seems to be used to
> configure the network device in GRUB (grub_net_configure_by_dhcp_ack()
> seems only to consume pxe_mode->dhcp_ack).
>
> If the UEFI subsystem is initialized before using the 'dhcp' command the
> DHCP results are ignored.
>
> @Patrick:
> What do you use the protocol for? GRUB?
>
> Best regards
>
> Heinrich
>