VirtualBox

Changeset 76020 in vbox


Ignore:
Timestamp:
Dec 6, 2018 3:48:29 PM (6 years ago)
Author:
vboxsync
Message:

DevPCNet: Review comment.

File:
1 edited

Legend:

Unmodified
Added
Removed
  • trunk/src/VBox/Devices/Network/DevPCNet.cpp

    r71790 r76020  
    24412441                     * the buffer length of 0 is interpreted as a 4096-byte
    24422442                     * buffer.'' */
     2443                    /* r=michaln: Perhaps not quite right. The C-LANCE (Am79C90)
     2444                     * datasheet explains that the old LANCE (Am7990) ignored
     2445                     * the top four bits next to BCNT and a count of 0 was
     2446                     * interpreted as 4096. In the C-LANCE, that is still the
     2447                     * case if the top bits are all ones. If all 16 bits are
     2448                     * zero, the C-LANCE interprets it as zero-length transmit
     2449                     * buffer. It's not entirely clear if the later models
     2450                     * (PCnet-ISA, PCnet-PCI) behave like the C-LANCE or not.
     2451                     * It is possible that the actual behavior of the C-LANCE
     2452                     * and later hardware is that the buffer lengths are *16-bit*
     2453                     * two's complement numbers between 0 and 4096. AMD's drivers
     2454                     * in fact generally treat the length as a 16-bit quantity. */
    24432455                    LogRel(("PCNet#%d: pcnetAsyncTransmit: illegal 4kb frame -> ignoring\n", PCNET_INST_NR));
    24442456                    pcnetTmdStorePassHost(pThis, &tmd, PHYSADDR(pThis, CSR_CXDA(pThis)));
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