* Question concerning function illegal_highdma
@ 2016-03-08 10:32 Lino Sanfilippo
0 siblings, 0 replies; only message in thread
From: Lino Sanfilippo @ 2016-03-08 10:32 UTC (permalink / raw)
To: netdev; +Cc: Lino Sanfilippo, linux-kernel
Hi all,
while trying to understand the meaning of the net_device flag NETIF_F_HIGHDMA
I came across the function illegal_highdma() which seems to perform two tasks:
1. Check if a network interface is able to handle high memory pages
2. Check if a network interface is able to handle the resulting DMA addresses
What I dont understand is why both conditions are only checked if CONFIG_HIGHMEM is set.
For 1. this makes sense, of course. But why is 2. also only checked with CONFIG_HIGHMEM?
Should not 2. always be checked, regardless of whether high memory exists in the system or not?
Thanks for any enlightenment in advance!
Regards,
Lino
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