[Qemu-devel] [PATCH] Fix for commit 3f9cb1c14dc368f41447db5f78d6248c4f100ad4

[Naphtali Sprei <nsprei@redhat.com>]

Here's a patch to fix the issue introduced by me, as Reimar Döffinger pointed out,

Reimar Döffinger wrote:
> On Thu, Aug 13, 2009 at 03:01:20PM +0300, Naphtali Sprei wrote:
>> Bug fix for segfault when run as i82551 HW:
>> Use Extended TBD only when HW supports it (i82558 and up).
>>
>> Added assertions to guard from such buffer overflow
>> Introduce the MAX_TCB_BYTE_COUNT macro
>> Allocate buf big enough as HW needs (MAX_ETH_FRAME_SIZE -> MAX_TCB_BYTE_COUNT)
>>
>>
>> I don't feel 100% OK with the "s->device >= i82558B" condition
>> since it relies on the numeric (hex) value of those defines, which currently
>> is correct, but changes (which I don't forsee now) might break it.
> 
> It seems this was applied. Unfortunately this breaks things on FreeBSD.
> There seem to be multiple issues.
> First, the intel document says the 82551, 82550, 82559 models are all
> supersets of the 82558. Or in other words: they all support this
> feature.
> Only the 82557 does not.
> But then even for that the FreeBSD driver will fail.
> The reason for that is this line:
>     eeprom_contents[0xa] = 0x4000;
> the value here must be 0x01000 for all 82557 models it seems.

 Correct the logic of determining devices that supports
 extended TxCB: only the 82557 do not support it.

Signed-off-by: Naphtali Sprei <nsprei@redhat.com>
---
 hw/eepro100.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/hw/eepro100.c b/hw/eepro100.c
index c374931..287b462 100644
--- a/hw/eepro100.c
+++ b/hw/eepro100.c
@@ -575,6 +575,11 @@ static uint16_t eepro100_read_command(EEPRO100State * s)
 }
 #endif
 
+static bool device_supports_eTxCB(EEPRO100State * s)
+{
+    return (s->device != i82557B && s->device != i82557C);
+}
+
 /* Commands that can be put in a command list entry. */
 enum commands {
     CmdNOp = 0,
@@ -717,7 +722,7 @@ static void eepro100_cu_command(EEPRO100State * s, uint8_t val)
             } else {
                 /* Flexible mode. */
                 uint8_t tbd_count = 0;
-                if ((s->device >= i82558B) && !(s->configuration[6] & BIT(4))) {
+                if (device_supports_eTxCB(s) && !(s->configuration[6] & BIT(4))) {
                     /* Extended Flexible TCB. */
                     assert(tcb_bytes == 0);
                     for (; tbd_count < 2; tbd_count++) {
-- 
1.6.3.3