[Xen-devel] [patch merge tree] netfront needs more headroom

[Gerd Knorr <kraxel@xxxxxxx>]

  Hi,

Raised the headrum size from 200 to 512.  I've got "Received packet 
needs 120 bytes more headroom." in my syslog, so 200 is obviously too small.
Increased to 512 as the slab allocator gives out pieces of memory with 
sizes being powers of two, so the old allocation size already was 256 
and anything larger than that will end up being 512 anyway (unless we 
create our own memory pool with custom size ...)
cheers,

  Gerd

Subject: xen netfront driver needs more headroom
From: kraxel@xxxxxxx

Index: linux-2.6.14/drivers/xen/netfront/netfront.c
===================================================================
--- linux-2.6.14.orig/drivers/xen/netfront/netfront.c   2005-12-07 
16:26:12.000000000 +0100
+++ linux-2.6.14/drivers/xen/netfront/netfront.c        2005-12-07 
16:27:47.000000000 +0100
@@ -77,7 +77,7 @@
     } while (0)
 
 /* Allow headroom on each rx pkt for Ethernet header, alignment padding, ... */
-#define RX_HEADROOM 200
+#define RX_HEADROOM 512
 
 static unsigned long rx_pfn_array[NET_RX_RING_SIZE];
 static multicall_entry_t rx_mcl[NET_RX_RING_SIZE+1];

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