From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: Question regarding the DTLB Miss exceptions From: Michael Ellerman To: Bruce_Leonard@selinc.com In-Reply-To: References: Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-Q6sNPAkxF+AYdlIGb5Dc" Date: Thu, 08 Apr 2010 23:59:30 +1000 Message-ID: <1270735170.19546.2.camel@concordia> Mime-Version: 1.0 Cc: linuxppc-dev@lists.ozlabs.org Reply-To: michael@ellerman.id.au List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-Q6sNPAkxF+AYdlIGb5Dc Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2010-03-29 at 23:24 -0700, Bruce_Leonard@selinc.com wrote:=20 > I'm tracking a problem that's leading me through DSI and DTLB miss=20 > exceptions on an MPC8347 (e300c1 core), and I've come across an oddity=20 > that I'm hoping someone can explain. >=20 > When a DTLB Miss exception can't find a PTE for the virtual address being= =20 > written/read, it dummies up the SPRs for a DSI exception and then calls=20 > directly into the DSI exception code. Just before the DTLB miss code=20 > stores a value into DSISR it sets bit 2, which for a DSI exception is a=20 > reserved bit and should be cleared. There's no comment on the code=20 > (.../arch/powerpc/kernel/head_32.S line 619 of the 2.6.33-rc1 kernel). Ca= n=20 > anyone tell me why this bit is getting set? You mean: 616 DataAddressInvalid: 617 mfspr r3,SPRN_SRR1 618 rlwinm r1,r3,9,6,6 /* Get load/store bit */ 619 addis r1,r1,0x2000 = =20 620 mtspr SPRN_DSISR,r1 Is it trying to set DSISR_ISSTORE? #define DSISR_ISSTORE 0x02000000 /* access was a store */ = =20 cheers=20 --=-Q6sNPAkxF+AYdlIGb5Dc Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEABECAAYFAku94T4ACgkQdSjSd0sB4dITZACfbk0Rzg5Q5Wg1f9TcwX2DWgzO 9bMAn2bD6zTvc6Muc9Y33sGWtsE0K3kQ =Je0r -----END PGP SIGNATURE----- --=-Q6sNPAkxF+AYdlIGb5Dc--