Re: [PATCH 1/1] ixgbe: sync the first fragment unconditionally

[David Miller]

From: Firo Yang <firo.yang@xxxxxxxx>
Date: Tue, 6 Aug 2019 09:29:51 +0000

> In Xen environment, if Xen-swiotlb is enabled, ixgbe driver
> could possibly allocate a page, DMA memory buffer, for the first
> fragment which is not suitable for Xen-swiotlb to do DMA operations.
> Xen-swiotlb will internally allocate another page for doing DMA
> operations. It requires syncing between those two pages. Otherwise,
> we may get an incomplete skb. To fix this problem, sync the first
> fragment no matter the first fargment is makred as "page_released"
> or not.
> 
> Signed-off-by: Firo Yang <firo.yang@xxxxxxxx>

I don't understand, an unmap operation implies a sync operation.