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| author | Stefan Hajnoczi | 2022-11-17 17:55:54 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi | 2022-11-21 15:28:43 +0100 |
| commit | 6d71357a3b651ec9db126e4862b77e13165427f5 (patch) | |
| tree | 125f52b2e4b093921b4aacf87579943d2aa2582b /target | |
| parent | rtl8139: keep Tx command mode 0 and 1 separate (diff) | |
| download | qemu-6d71357a3b651ec9db126e4862b77e13165427f5.tar.gz qemu-6d71357a3b651ec9db126e4862b77e13165427f5.tar.xz qemu-6d71357a3b651ec9db126e4862b77e13165427f5.zip | |
rtl8139: honor large send MSS value
The Large-Send Task Offload Tx Descriptor (9.2.1 Transmit) has a
Large-Send MSS value where the driver specifies the MSS. See the
datasheet here:
http://realtek.info/pdf/rtl8139cp.pdf
The code ignores this value and uses a hardcoded MSS of 1500 bytes
instead. When the MTU is less than 1500 bytes the hardcoded value
results in IP fragmentation and poor performance.
Use the Large-Send MSS value to correctly size Large-Send packets.
Jason Wang <jasowang@redhat.com> noticed that the Large-Send MSS value
mask was incorrect so it is adjusted to match the datasheet and Linux
8139cp driver.
This issue was discussed in the past here:
https://lore.kernel.org/all/20161114162505.GD26664@stefanha-x1.localdomain/
Reported-by: Russell King - ARM Linux <linux@armlinux.org.uk>
Reported-by: Tobias Fiebig <tobias+git@fiebig.nl>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1312
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20221117165554.1773409-4-stefanha@redhat.com>
Diffstat (limited to 'target')
0 files changed, 0 insertions, 0 deletions