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Date:      Wed, 26 Dec 2012 20:16:02 -0800
From:      Oleksandr Tymoshenko <gonzo@bluezbox.com>
To:        Daisuke Aoyama <aoyama@peach.ne.jp>
Cc:        freebsd-arm@freebsd.org
Subject:   Re: FreeBSD/armv6z/clang on Raspberry Pi 512MB (with U-Boot + ubldr)
Message-ID:  <BE93F553-E060-45E5-90FE-39AAD1325BAB@bluezbox.com>
In-Reply-To: <2BA73CBF02B04DD19D08CDFC556B8750@ad.peach.ne.jp>
References:  <B5F827FF91C94FF2AFEE00194A2BB2C5@ad.peach.ne.jp> <B508111FCE534B2CBA61F4D1EC1078D3@ad.peach.ne.jp> <E42823D3-D405-40E7-B4CF-75DC947AC119@bluezbox.com> <2BA73CBF02B04DD19D08CDFC556B8750@ad.peach.ne.jp>

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On 2012-12-26, at 7:52 PM, Daisuke Aoyama <aoyama@peach.ne.jp> wrote:

>> PTE sync - related part, Im not sure it's strictly required. We use =
WT caches for page tables
>> so we should be OK without implicit sync operations for them. I hope =
somebody
>> more clueful can confirm/disprove this.
>=20
> Some digging, I notice "Invalidate Entire Instruction Cache" works =
without segfault.
> So, Invalidate D-cache is no effect :)
>=20
> It seems following should work for this issue:
>=20
>       mov     r0, #0
>       mcr     p15, 0, r0, c7, c5, 0           /* Invalidate Entire =
Instruction Cache */
>       mcr     p15, 0, r0, c7, c10, 4          /* Data Synchronization =
Barrier */
>=20
> Try this code instead of CF_ICACHE_SYNC.
> I don't know side effect of Invalidate I-cache, but it works.
> Also I don't know whether DSB is required or not.
>=20
> For test, using NFS or HDD/SDD is BAD idea for system stress.
> You must use SD(mmc) or USB memory. Serial console is recommended for =
interrupt test.
> Here is simple test from serial console:
>=20
> # rm -rf /var/db/portsnap /usr/ports
> # mkdir /var/db/portsnap
> # portsnap fetch
> # portsnap extract
> # cd /usr/ports/shells/bash
> # make BATCH=3Dy
>=20
> If your kernel is really stable, it should finish without any problems =
with SD/mmc.
>=20

Hmm, I saw problems with i-caches with kernel with WB cache enabled =
instead of WT.=20
This patch fixed it for me:

http://people.freebsd.org/~gonzo/arm/patches/pmapv6-icache.diff
It invalidates i-caches only when new mapping is created, not on every =
switch so=20
it should be less taxing on performance.

Could you test it on your setup?=20=



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