When running on a system with an ACPI-provided system-specific MAC
address, iPXE will apply this address to an ECM or NCM USB NIC. If
iPXE has been chainloaded from a previous stage that does not
understand the ACPI MAC mechanism then this can result in iPXE using a
different MAC address than the previous stage, which is surprising to
users.
Attempt to minimise surprise by allowing the MAC address found in a
cached DHCPACK packet to override a temporary MAC address, if the
DHCPACK MAC address matches the network device's permanent MAC
address. When a previous stage has chosen to use the network device's
permanent MAC address (e.g. because it does not understand the ACPI
MAC mechanism), this will cause iPXE to make the same choice.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Commit cd3de55 ("[efi] Record cached DHCPACK from loaded image's
device handle, if present") added the ability for a chainloaded UEFI
iPXE to reuse an IPv4 address and DHCP options previously obtained by
a built-in PXE stack, without needing to perform a second DHCP
request.
Extend this to also record the cached ProxyDHCPOFFER and PXEBSACK
obtained from the EFI_PXE_BASE_CODE_PROTOCOL instance installed on the
loaded image's device handle, if present.
This allows a chainloaded UEFI iPXE to reuse a boot filename or other
options that were provided via a ProxyDHCP or PXE boot server
mechanism, rather than by standard DHCP.
Tested-by: Andreas Hammarskjöld <junior@2PintSoftware.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Split out the portions of cachedhcp.c that can be shared between BIOS
and UEFI (both of which can provide a buffer containing a previously
obtained DHCP packet, and neither of which provide a means to
determine the length of this DHCP packet).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown