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Re: kern/54486: athn driver panics on arm
The following reply was made to PR kern/54486; it has been noted by GNATS.
From: Nick Hudson <nick.hudson%gmx.co.uk@localhost>
To: Rin Okuyama <rokuyama%meiji.ac.jp@localhost>, matthew green <mrg%eterna.com.au@localhost>,
Andreas Gustafsson <gson%gson.org@localhost>
Cc: Christos Zoulas <christos%astron.com@localhost>, "maya%NetBSD.org@localhost"
<maya%NetBSD.org@localhost>, "gnats-bugs%netbsd.org@localhost" <gnats-bugs%netbsd.org@localhost>
Subject: Re: kern/54486: athn driver panics on arm
Date: Sun, 25 Aug 2019 08:54:35 +0100
On 24/08/2019 13:01, Rin Okuyama wrote:
> On 2019/08/24 20:11, matthew green wrote:
>>> I found some related discussion in the port-arm archives, starting at:
>>> My understanding of that discussion is that there are two alternative
>>> correct fixes: either apply the patch from the above message to add
>>> -mno-unaligned-access to CFLAGS, or stop using PMAP_NOCACHE in
>>> bus_dma.c as mentioned in:
>>> The problem is that *neither* has been done. Since the patch is less
>>> likely to have bad side effects, I think we should apply the patch
>>> now, and if or when the pmap change is ever made, the patch can be
>> apparently i agreed with you back in january. Rin, can you
>> commit your change for now. at least until we fix pmap..
> IMO, adding -mno-unaligned-access to CFLAGS is not a correct fix,
> although affects on performance seems negligible as far as I can
> see (I guess that benefits by ability of unaligned access are
> canceled by penalty of it).
> A real fix should be using cacheble memory for DMA buffer. However,
> it breaks some drivers, at least, awge(4) and vchiq(4). Now, Nick
> is working on it.
> Nick, how is the progress? If it takes a long time, we need to
> consider a workaround of -mno-unaligned-access (and pull it up
> into netbsd-9).
My focus is elsewhere at the moment, so feel free to apply the workaround.
Perhaps we can compile a handful of drivers with -mno-unaligned-access
and not the whole kernel?
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