* [Qemu-devel] [PATCH] spapr-vlan: Don't touch last entry in buffer list
@ 2014-08-22 1:50 Anton Blanchard
2014-08-26 3:02 ` David Gibson
2014-08-27 11:07 ` Alexander Graf
0 siblings, 2 replies; 3+ messages in thread
From: Anton Blanchard @ 2014-08-22 1:50 UTC (permalink / raw)
To: agraf, david, aik, paulus; +Cc: qemu-ppc, qemu-devel
The last 8 bytes of the buffer list is defined to contain the number
of dropped frames. At the moment we use it to store rx entries,
which trips up ethtool -S:
rx_no_buffer: 9223380832981355136
Fix this by skipping the last buffer list entry.
Signed-off-by: Anton Blanchard <anton@samba.org>
---
diff --git a/hw/net/spapr_llan.c b/hw/net/spapr_llan.c
index 2d47df6..23c47d3 100644
--- a/hw/net/spapr_llan.c
+++ b/hw/net/spapr_llan.c
@@ -72,7 +72,14 @@ typedef uint64_t vlan_bd_t;
#define VLAN_RXQ_BD_OFF 0
#define VLAN_FILTER_BD_OFF 8
#define VLAN_RX_BDS_OFF 16
-#define VLAN_MAX_BUFS ((SPAPR_TCE_PAGE_SIZE - VLAN_RX_BDS_OFF) / 8)
+/*
+ * The final 8 bytes of the buffer list is a counter of frames dropped
+ * because there was not a buffer in the buffer list capable of holding
+ * the frame. We must avoid it, or the operating system will report garbage
+ * for this statistic.
+ */
+#define VLAN_RX_BDS_LEN (SPAPR_TCE_PAGE_SIZE - VLAN_RX_BDS_OFF - 8)
+#define VLAN_MAX_BUFS (VLAN_RX_BDS_LEN / 8)
#define TYPE_VIO_SPAPR_VLAN_DEVICE "spapr-vlan"
#define VIO_SPAPR_VLAN_DEVICE(obj) \
@@ -119,7 +126,7 @@ static ssize_t spapr_vlan_receive(NetClientState *nc, const uint8_t *buf,
do {
buf_ptr += 8;
- if (buf_ptr >= SPAPR_TCE_PAGE_SIZE) {
+ if (buf_ptr >= (VLAN_RX_BDS_LEN + VLAN_RX_BDS_OFF)) {
buf_ptr = VLAN_RX_BDS_OFF;
}
@@ -397,7 +404,7 @@ static target_ulong h_add_logical_lan_buffer(PowerPCCPU *cpu,
do {
dev->add_buf_ptr += 8;
- if (dev->add_buf_ptr >= SPAPR_TCE_PAGE_SIZE) {
+ if (dev->add_buf_ptr >= (VLAN_RX_BDS_LEN + VLAN_RX_BDS_OFF)) {
dev->add_buf_ptr = VLAN_RX_BDS_OFF;
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] spapr-vlan: Don't touch last entry in buffer list
2014-08-22 1:50 [Qemu-devel] [PATCH] spapr-vlan: Don't touch last entry in buffer list Anton Blanchard
@ 2014-08-26 3:02 ` David Gibson
2014-08-27 11:07 ` Alexander Graf
1 sibling, 0 replies; 3+ messages in thread
From: David Gibson @ 2014-08-26 3:02 UTC (permalink / raw)
To: Anton Blanchard; +Cc: aik, qemu-ppc, paulus, agraf, qemu-devel
[-- Attachment #1: Type: text/plain, Size: 706 bytes --]
On Fri, Aug 22, 2014 at 11:50:57AM +1000, Anton Blanchard wrote:
> The last 8 bytes of the buffer list is defined to contain the number
> of dropped frames. At the moment we use it to store rx entries,
> which trips up ethtool -S:
>
> rx_no_buffer: 9223380832981355136
>
> Fix this by skipping the last buffer list entry.
>
> Signed-off-by: Anton Blanchard <anton@samba.org>
Huh. I obviously missed that bit of the llan spec in PAPR.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
[-- Attachment #2: Type: application/pgp-signature, Size: 819 bytes --]
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] spapr-vlan: Don't touch last entry in buffer list
2014-08-22 1:50 [Qemu-devel] [PATCH] spapr-vlan: Don't touch last entry in buffer list Anton Blanchard
2014-08-26 3:02 ` David Gibson
@ 2014-08-27 11:07 ` Alexander Graf
1 sibling, 0 replies; 3+ messages in thread
From: Alexander Graf @ 2014-08-27 11:07 UTC (permalink / raw)
To: Anton Blanchard, david, aik, paulus; +Cc: qemu-ppc, qemu-devel
On 22.08.14 03:50, Anton Blanchard wrote:
> The last 8 bytes of the buffer list is defined to contain the number
> of dropped frames. At the moment we use it to store rx entries,
> which trips up ethtool -S:
>
> rx_no_buffer: 9223380832981355136
>
> Fix this by skipping the last buffer list entry.
>
> Signed-off-by: Anton Blanchard <anton@samba.org>
Thanks, applied to ppc-next.
Alex
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2014-08-27 11:07 UTC | newest]
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2014-08-22 1:50 [Qemu-devel] [PATCH] spapr-vlan: Don't touch last entry in buffer list Anton Blanchard
2014-08-26 3:02 ` David Gibson
2014-08-27 11:07 ` Alexander Graf
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