From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4575BFBF.1080306@domain.hid> Date: Tue, 05 Dec 2006 19:51:43 +0100 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Adeos-main] [PATCH] I-pipe tracer for ARM References: <4575A2C0.6000305@domain.hid> <200612051934.14391.Sebastian.Smolorz@domain.hid> In-Reply-To: <200612051934.14391.Sebastian.Smolorz@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigDDC32145D423743581E22598" Sender: jan.kiszka@domain.hid List-Id: General discussion about Adeos List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Sebastian Smolorz Cc: Gilles Chanteperdrix , adeos-main@gna.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigDDC32145D423743581E22598 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Sebastian Smolorz wrote: > Jan Kiszka wrote: >> Sebastian Smolorz wrote: >>> Gilles Chanteperdrix wrote: >>>> Jan Kiszka wrote: >>>>> Gilles Chanteperdrix wrote: >>>>>> Jan Kiszka wrote: >>>>>>> Sebastian Smolorz wrote: >>>>>>>> Jan Kiszka wrote: >>>>>>>>> Are you tracing into vmalloc'ed memory? >>>>>>>> Yes, without CONFIG_IPIPE_TRACE_VMALLOC the system does not boot= =2E >>>>>>> Hmm, makes me wonder of some laziness of the page mapping or a >>>>>>> missing lock-against-swapping causes this. Could you have a close= r >>>>>>> look at the tracer code if we are lacking some magic for the vmal= loc >>>>>>> trace buffer (compare to the xnheap code, e.g.)? >>>>>> This is a known issue, the ARM architecture lacks the set_pgdir >>>>>> function, needed in mm/vmalloc.c to workaround the lazy page mappi= ng >>>>>> of vmalloced areas. >>>>> Would vmalloc+memset help to be safe for the remaining system runti= me? >>>> Probably not, the vmalloced area is added only to the page table of = the >>>> process that calls vmalloc, it is added to other processes table pag= e >>>> only once they use it. >>> Are there any alternatives? Or do we have to live with this restricti= on? >> Try if smaller CONFIG_IPIPE_TRACE_SHIFT makes it boot without >> CONFIG_IPIPE_TRACE_VMALLOC. >=20 > I already tried that but it didn't help. First with IPIPE_TRACE_SHIFT s= et to=20 > 10 and after modifying Kconfig.debug with a value of 5. Booting impossi= ble. What about starting disabled and arming the tracer later via /proc/ipipe/trace/enable? This sounds like it's not a size issue (TRACE_SHIFT=3D5 is ridiculous small), rather some memory section is accessed too early. If it works we could postpone enabling to __ipipe_init_tracer by default (like it is done for TRACE_VMALLOC). I cannot imagine use cases for the tracer ATM that would benefit from early tracing. Jan --------------enigDDC32145D423743581E22598 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFdb+/niDOoMHTA+kRAlRIAJ49B8klAtn8ZXhwSVDI72gF/kVIZwCaAhat e/17fCBSzyV0BL9qWyJ6114= =XPE9 -----END PGP SIGNATURE----- --------------enigDDC32145D423743581E22598--