Hi,
Please show us how you're manipulating the mbufs.
You should not be getting page faults unless you're doing
something wrong.
A good idea would also be to check the fault virtual
address and enable debugging support in your kernel in order
to be able to analyze the situation as much as you can.
Regards,
Bosko.
----- Original Message -----
From: "Marcus Vinícius Midena Ramos" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, December 28, 2000 8:58 AM
Subject: Intel ethernet driver source code
> Hello,
>
> I am developing an application to measure the performance of an IP
> communications network, accounting for packet loss rate and transmission
> delay values between any two sites on a net. This work resembles that of
> www.advanced.org and is also based on IETF's IPPM initiative.
>
> One of the goals is to insert a GPS timestamp on the packets to be
> transmitted as late as possible before they are put on the wire. This
> means I cannot do this job on the application level. Instead, this has
> to be done on the ethernet driver level in order to achieve the maximum
> accuracy, specially when the measurement machine is under heavy load.
>
> I've studied the "if_fxp.c" (Intel ethernet driver) source code plus
> Stevens' TCP Illustrated vol. 2, which helped me get a good
> understanding of the data structures manipulated by this code. My aim
> now is to insert the GPS timestamps on the packets to be transmitted
> right before they go to the interface.
>
> To do this, I am trying to modify the driver source code to achieve the
> following objectives: (1) read the contents of the mbufs in order to
> identify the ones that hold the packets to be transmitted, and (2)
> insert the timestamps on those ellegible for so.
>
> However, any access to mbufs from inside the driver causes an error
> message "page fault while in kernel mode" to be displayed the new kernel
> is booted. It then enters a loop, trying to reboot forever.
>
> I guess the mbufs are in an area somehow protected by the kernel, which
> prevents even the driver to have access to it. May question is: how can
> I go around this problem and be able to read and change the contents of
> the mbufs from inside the driver ?
>
> Thank you very much.
> Marcus.
>
>
>
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