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[lwip-users] RE: [lwip] Recent change in pbuf.c
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From: |
Ivarsson Magnus |
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Subject: |
[lwip-users] RE: [lwip] Recent change in pbuf.c |
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Date: |
Wed, 08 Jan 2003 23:47:31 -0000 |
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I would like the PBUF_LINK to stay at least on 4 bytes in order for the PPP
interface to work without chaining every single packet. Those who want to
preserve the unneccesary memory in implementations without the need for
PBUF_LINK can define it to zero in for example lwipopts.h but the design of the
network interface drivers should not rely on it.
BR, Magnus
-----Original Message-----
From: David Haas [mailto:address@hidden
Sent: den 2 december 2002 22:02
To: address@hidden
Subject: [lwip] Recent change in pbuf.c
There was a recent change in pbuf.c by jani which says: "fix pbuf_alloc for
layer PBUF_LINK". This change has caused some problems for me and I want to
explore why.
In my ethernet driver I am using PBUF_LINK when allocating pbufs for the
receive buffers. This recent change will reserve bytes in the front of the
pbuf, presumably for a link-level header. However, the ethernet chip will be
putting a link-level header in the packet already. So I would claim that the
offset for PBUF-LINK should be 0 (which it was before it was changed). Now, I
could change my allocation to PBUF_RAW, but I would claim that would wrong.
Any comment?
David Haas
NBS Card Technology
70 Eisenhower Drive,
Paramus, NJ 07652
Voice: 201-845-7373 x183
Fax: 201-845-3337
email: address@hidden <mailto:address@hidden>
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<DIV><SPAN class=725025207-03122002><FONT face=Arial color=#0000ff size=2>I
would like the PBUF_LINK to stay at least on 4 bytes in order for the PPP
interface to work without chaining every single packet. Those who want to
preserve the unneccesary memory in implementations without the need for
PBUF_LINK can define it to zero in for example lwipopts.h but the design of the
network interface drivers should not rely on it.</FONT></SPAN></DIV>
<DIV><SPAN class=725025207-03122002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=725025207-03122002><FONT face=Arial color=#0000ff size=2>BR,
Magnus</FONT></SPAN></DIV>
<DIV><SPAN class=725025207-03122002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid;
MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> David Haas
[mailto:address@hidden<BR><B>Sent:</B> den 2 december 2002
22:02<BR><B>To:</B> address@hidden<BR><B>Subject:</B> [lwip] Recent change in
pbuf.c<BR><BR></FONT></DIV>
<DIV><FONT size=2>There was a recent change in pbuf.c by jani which says:
"fix
pbuf_alloc for layer PBUF_LINK". This change has caused some problems for me
and I want to explore why.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>In my ethernet driver I am using PBUF_LINK when allocating
pbufs for the receive buffers. This recent change will reserve bytes in the
front of the pbuf, presumably for a link-level header. However, the ethernet
chip will be putting a link-level header in the packet already. So I would
claim that the offset for PBUF-LINK should be 0 (which it was before it was
changed). Now, I could change my allocation to PBUF_RAW, but I would claim
that would wrong.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Any comment?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2>David Haas<BR>NBS Card Technology<BR>70 Eisenhower
Drive,<BR>Paramus, NJ 07652<BR>Voice: 201-845-7373 x183<BR>Fax:
201-845-3337<BR>email: <A
href="mailto:address@hidden";>address@hidden</A><BR></FONT></DIV></BLOCKQUOTE></BODY></HTML>
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