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Hi Nainar,<br>
<br>
What do you mean by "controllers do not support recycling of Tx
buffers"?<br>
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.<br>
After UNDI/SNP successfully transmits the packet, it is expected to
give it back via UNDI->GetStatus().<br>
<br>
Adding network controller (NIC) and UNDI into the picture.<br>
<br>
1. UNDI->Transmit() gets a single Tx buffer to put on the wire.<br>
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.<br>
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.<br>
<br>
Summing the above - Tx buffer recycling is purely a SW feature. I do
not understand your request nor find it valid.<br>
<br>
Thanks,<br>
Maciej<br>
<br>
<div class="moz-cite-prefix">On 24-Nov-20 15:30, Sivaraman Nainar
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:B4DE137BDB63634BAC03BD9DE765F19702B4B9B3AA@VENUS1.in.megatrends.com">
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<div class="WordSection1">
<p class="MsoNormal">Hello all:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">MNPDxe supported with the Recycle buffer
support from the below git commit,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a
href="https://github.com/tianocore/edk2/commit/0507449955c5c629cec196b62986afbb91203ed9#diff-fb5b97ad38efea22f5ddd745f6e43ebdb509dc4a5aef81997ba53af5f918a47b"
moz-do-not-send="true">https://github.com/tianocore/edk2/commit/0507449955c5c629cec196b62986afbb91203ed9#diff-fb5b97ad38efea22f5ddd745f6e43ebdb509dc4a5aef81997ba53af5f918a47b</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">But many network controllers does not
support the Recycling Tx Buffers which will cause the PXE
Download failure or HTTP Boot failure.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Can this feature can be controlled by a
Dynamic PCD so that the same code can work for controller
which does not support Tx Buffer Recycling.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks<o:p></o:p></p>
<p class="MsoNormal">Siva<o:p></o:p></p>
</div>
</blockquote>
<br>
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