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Subject: Re: svn commit: r339382 - projects/power8_bringup_hacks/sys/dev/bge
To: Leandro Lupori <luporl@FreeBSD.org>, src-committers@freebsd.org,
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References: <201810161636.w9GGa3Nl001743@repo.freebsd.org>
From: John Baldwin <jhb@FreeBSD.org>
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Date: Tue, 16 Oct 2018 09:55:13 -0700
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On 10/16/18 9:36 AM, Leandro Lupori wrote:
> Author: luporl
> Date: Tue Oct 16 16:36:02 2018
> New Revision: 339382
> URL: https://svnweb.freebsd.org/changeset/base/339382
> 
> Log:
>   bge(4): limit DMA address to 2GB
>   
>   This is a temporary hack, to avoid POWER8 Broadcom NICs from becoming
>   unusable after transferring a reasonable amount of data.
>   The issue is the same as that of AHCI, where DMA addresses above 2GB
>   do not work and causes PCI errors.

Is the issue bge specific or specific to the PCI chipset in these boxes?
If the latter, the better approach would be to set the limit in a tag the
chipset provides that all child devices would then inherit.

-- 
John Baldwin