What do you mean by "controllers do not support recycling of Tx
buffers"?
MNP provides a transmit buffer to SNP (and with EDK2's SNP also to
UNDI) and at this point it is considered owned by SNP/UNDI.
After UNDI/SNP successfully transmits the packet, it is expected to
give it back via UNDI->GetStatus().
Adding network controller (NIC) and UNDI into the picture.
1. UNDI->Transmit() gets a single Tx buffer to put on the wire.
2. If a NIC has a pre-allocated region for Tx buffers and cannot
dynamically swap them out, UNDI->Transmit() should copy the Tx
buffer into appropriate region. UNDI driver should also store that
Tx buffer somewhere within the driver, where it will be accessible
by UNDI->GetStatus() function.
3. After successful transmit of Tx buffer, on next
UNDI->GetStatus() with PXE_OPFLAGS_GET_TRANSMITTED_BUFFERS
OpFlag, driver should put that Tx buffer address in PXE_CDB.DBAddr
provided to UNDI->GetStatus() as a parameter.
Summing the above - Tx buffer recycling is purely a SW feature. I do
not understand your request nor find it valid.
Thanks,
Maciej
On 24-Nov-20 15:30, Sivaraman Nainar
wrote:
Hello all:
MNPDxe supported with the Recycle buffer
support from the below git commit,