[3/5] Add support for receiving via receive buffers. While the Intel documentation claims this is unsupported, the OS X drivers use it, causing an assertion failure since rx buffer size is 0.

This adds support for some kind of receive buffers "flexible
mode". The Intel documentation as I read it claims that no such mode exist
for receive, but the fact that those (working with real hardware I
expect) drivers use it contradicts that...
This _definitely_ is necessary to support these AppleIntel8255x drivers.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
---
 hw/eepro100.c |   27 ++++++++++++++++++++++++---
 1 files changed, 24 insertions(+), 3 deletions(-)

On Tue, 11 Aug 2009, Reimar D?ffinger wrote:

> This adds support for some kind of receive buffers "flexible
> mode". The Intel documentation as I read it claims that no such mode exist
> for receive, but the fact that those (working with real hardware I
> expect) drivers use it contradicts that...
> This _definitely_ is necessary to support these AppleIntel8255x drivers.
> 
> Signed-off-by: Reimar D?ffinger <Reimar.Doeffinger@gmx.de>
> ---
>  hw/eepro100.c |   27 ++++++++++++++++++++++++---
>  1 files changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/eepro100.c b/hw/eepro100.c
> index f619d36..5620bc7 100644
> --- a/hw/eepro100.c
> +++ b/hw/eepro100.c
> @@ -153,6 +153,14 @@ typedef struct {
>      char packet[MAX_ETH_FRAME_SIZE + 4];
>  } eepro100_rx_t;
>  
> +/* Receive buffer descriptor. */
> +typedef struct {
> +    uint32_t count;
> +    uint32_t link;
> +    uint32_t buffer;
> +    uint32_t size;
> +} eepro100_rbd_t;

_t suffix aside (the whole file is quite tainted in this regard) and from
skimming over the rest of the file it appears that this structure is
shared with guest, even though it's neatly/(and for some definition of 
natural)naturally aligned, i believe this is dodgy. Then again maybe just
like _t the existing code already expects things to be rosy in this
regard.

> +
>  typedef struct {
>      uint32_t tx_good_frames, tx_max_collisions, tx_late_collisions,
>          tx_underruns, tx_lost_crs, tx_deferred, tx_single_collisions,
> @@ -218,6 +226,7 @@ typedef struct {
>      /* (ru_base + ru_offset) address the RFD in the Receive Frame Area. */
>      uint32_t ru_base;           /* RU base address */
>      uint32_t ru_offset;         /* RU address offset */
> +    uint32_t rbd_addr;
>      uint32_t statsaddr;         /* pointer to eepro100_stats_t */
>      eepro100_stats_t statistics;        /* statistical counters */
>  #if 0
> @@ -843,6 +852,7 @@ static void eepro100_ru_command(EEPRO100State * s, uint8_t val)
>          }
>          set_ru_state(s, ru_ready);
>          s->ru_offset = s->pointer;
> +        s->rbd_addr = 0;
>          logout("val=0x%02x (rx start)\n", val);
>          break;
>      case RX_RESUME:
> @@ -1512,7 +1522,19 @@ static ssize_t nic_receive(VLANClientState *vc, const uint8_t * buf, size_t size
>      cpu_physical_memory_read(s->ru_base + s->ru_offset, (uint8_t *) & rx,
>                               offsetof(eepro100_rx_t, packet));
>      uint16_t rfd_command = le16_to_cpu(rx.command);
> -    uint16_t rfd_size = le16_to_cpu(rx.size);
> +    uint32_t rfd_size = le16_to_cpu(rx.size);
> +    uint32_t dst_addr = s->ru_base + s->ru_offset + offsetof(eepro100_rx_t, packet);
> +    if (rfd_command & 8) {
> +        // argh! Flexible mode. Intel docs say it is not support but the Mac OS driver uses it anyway.
                                                            support_ed_ perhaps?

> +        eepro100_rbd_t rbd;
> +        if (!s->rbd_addr)
> +            s->rbd_addr = le32_to_cpu(rx.rx_buf_addr);
> +        cpu_physical_memory_read(s->rbd_addr, (uint8_t *) & rbd, sizeof(rbd));
> +        rfd_size = le32_to_cpu(rbd.size);
> +        dst_addr = le32_to_cpu(rbd.buffer);
> +        stl_phys(s->rbd_addr + offsetof(eepro100_rbd_t, count), size | 0x8000);
> +        s->rbd_addr = le32_to_cpu(rbd.link);
> +    }
>      assert(size <= rfd_size);
>      if (size < 64) {
>          rfd_status |= 0x0080;
> @@ -1528,8 +1550,7 @@ static ssize_t nic_receive(VLANClientState *vc, const uint8_t * buf, size_t size
>      assert(!(s->configuration[18] & 4));
>      /* TODO: check stripping enable bit. */
>      //~ assert(!(s->configuration[17] & 1));
> -    cpu_physical_memory_write(s->ru_base + s->ru_offset +
> -                              offsetof(eepro100_rx_t, packet), buf, size);
> +    cpu_physical_memory_write(dst_addr, buf, size);
>      s->statistics.rx_good_frames++;
>      eepro100_fr_interrupt(s);
>      s->ru_offset = le32_to_cpu(rx.link);
>