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Re: kern/37884: nvidia ehci umass

On Sun, Jan 27, 2008 at 05:05:03PM +0000, Martin Husemann wrote:
> The following reply was made to PR kern/37884; it has been noted by GNATS.
> From: Martin Husemann <>
> To: Izumi Tsutsui <>
> Cc:,,
> Subject: Re: kern/37884: nvidia ehci umass
> Date: Sun, 27 Jan 2008 18:04:01 +0100
>  On Mon, Jan 28, 2008 at 01:43:46AM +0900, Izumi Tsutsui wrote:
>  > According to Microsoft KB925528, NVIDIA echi seems to have a bug
>  > which can't do DMA against memory higher than 2G physicall address.

Unless some of my 1GiB of physical memory (the Socket 754 northbridge
can only handle 2GiB anyway) is placed up there, I shouldn't be
having this issue.

It also doesn't explain how it is very easy to trigger with
flash drives, and hard to trigger with hard drives.

>  Oh, great, that would explain it.
>  > Maybe we could handle the quirk by MI bus_dmatag_subregion(9)
>  > like if_bce.c, but the next problem is that ehci(4) driver
>  > completely lacks bus_dmamap_sync(9) calls, as noted in
>  > sys/dev/usb/TODO.

But that might be causing it, the longer latency of a hard
drive may allow inconsistent cache to get evicted naturally.

But then why does it only happen with nvidia controllers?

>  Yes, that sounds like the way to go. I have an affected machine but won't
>  come around to it within the next few weeks, so everyone is invited to
>  beat me to this.

Well, now that I know where the issue may lie, I could try fixing it myself,
however, I'm not familiar with USB host controllers yet.

        Jonathan Kollasch

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