RTL8169: Difference between revisions

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@@ Line 134: / Line 134: @@
          else
            Rx_Descriptors[i].command = (OWN | (rx_buffer_len & 0x3FFF));
-         Rx_Descriptors[i].low_buf = (unsigned int)&packet_buffer_address; /* This is where the packet data will go */
+         /** packet_buffer_address is the *physical* address for the buffer */
+         Rx_Descriptors[i].low_buf = (unsigned int)&packet_buffer_address;
          Rx_Descriptors[i].high_buf = 0;
          /* If you are programming for a 64-bit OS, put the high memory location in the 'high_buf' descriptor area */
@@ Line 159: / Line 161: @@
      /* offset 0x20 == Transmit Descriptor Start Address Register
-        offset 0xE4 == Receive Descriptor Start Address Register */
+        offset 0xE4 == Receive Descriptor Start Address Register
+        Again, these are *physical* addresses. This code assumes physical==linear, this is
+        typically not the case in real world kernels
+     */
      outportl(ioaddr + 0x20, (unsigned long)&Tx_Descriptors[0]; /* Tell the NIC where the first Tx descriptor is */
      outportl(ioaddr + 0xE4, (unsigned long)&Rx_Descriptors[0]; /* Tell the NIC where the first Rx descriptor is */

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