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Thu, 2 Apr 2020 23:07:02 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 691807805C; Thu, 2 Apr 2020 23:06:48 +0000 (GMT) Received: from LeoBras (unknown [9.85.174.86]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 2 Apr 2020 23:06:47 +0000 (GMT) Message-ID: <6b4a4a0d4f7af723d0a5a12f4267717a507ce3f0.camel@linux.ibm.com> Subject: Re: [PATCH v3 1/1] powerpc/kernel: Enables memory hot-remove after reboot on pseries guests From: Leonardo Bras To: "Oliver O'Halloran" Date: Thu, 02 Apr 2020 20:06:41 -0300 In-Reply-To: References: <20200402195156.626430-1-leonardo@linux.ibm.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-LbIuD+NSE0mfSgDYZOtG" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-02_13:2020-04-02, 2020-04-02 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 impostorscore=0 suspectscore=0 adultscore=0 priorityscore=1501 mlxscore=0 lowpriorityscore=0 clxscore=1015 spamscore=0 mlxlogscore=930 malwarescore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004020166 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linux Kernel Mailing List , Greg Kroah-Hartman , Claudio Carvalho , Bharata B Rao , Paul Mackerras , Hari Bathini , Nathan Fontenot , Thomas Gleixner , linuxppc-dev , Allison Randal Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" --=-LbIuD+NSE0mfSgDYZOtG Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hello Oliver, thank you for the feedback. Comments inline: On Fri, 2020-04-03 at 09:46 +1100, Oliver O'Halloran wrote: >=20 > I don't really understand why the flag is needed at all. According to > PAPR any memory provided by dynamic reconfiguration can be hot-removed > so why aren't we treating all DR memory as hot removable? The only > memory guaranteed to be there 100% of the time is what's in the > /memory@0 node since that's supposed to cover the real mode area. All LMBs are listed in DR memory, even the base memory. The v1 of the patch would work this way, as qemu would configure it's DR memory with (DRC_INVALID | RESERVED) flags and the hot-added memory with (ASSIGNED) flag. Looking for assigned flag would be enough. But as of today, PowerVM doesn't seem to work that way.=20 When you boot a PowerVM virtual machine with Linux, all memory is added with the same flags (ASSIGNED). To create a solution that doesn't break PowerVM, this new flag was made necessary. Best regards, Leonardo Bras --=-LbIuD+NSE0mfSgDYZOtG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEMdeUgIzgjf6YmUyOlQYWtz9SttQFAl6GcAEACgkQlQYWtz9S ttSDaxAAleKBaZ21PxBQBe/pKqmPitbu7ok6nwICUsc9WhvezbRZQX/W9R3ghKQ6 +AcPpO4eVPq6K5kJDP8uPD2SxGGpYcwgDIrPlfInjdM00PzmujceFyAvglXGE6PB 9ZqAEsZsRNZIG5H1ge+H894jdLn+YMqQmO+tdNMyUqd/tSHh+FeXe9tvdM/KERo0 5OdDkFxUEsUD1W57uARIlM67J+/hKdAqgmr6rKnubQ42PsF4qkHussd9T79BiCeL bEdrkwVKTA5vdrUQND1uzT9tS75lW3pwZNW/JtQmqZaMHri0S+zjlgkueSs/tUUo X44fCVHs9xxZA0ZN3cQGnDWoASzn5WDvcSCKOhZYowGiSaHBfaoLkDhWBCmR9G+v lPeGVRx3gLRU91NCPnGYCg4b1rrfGZeyQB8gq4cmA8ejzCbUTCI78ooO3rZwdnmT evrLS4O3gDAfQXmkAMHYaz/ZV5Vvvc38psj5e7OMiCuxH5T52Fe34C/WWFZewZ9q tSFP2wQ03SS/BRW5CYhztf3J112vDxfLTD0OnHLWboBAbAlQTR3O//flG6e5y3RA 0aMWA/4YzL0tB/+1/c+UO0Vwmv+GT3HICs8O7ctU2tnowJWk5tBuj1Oz1+Thvn+O X/tnaZNnjPhv3Y3T0UBYWspFgpjEWqvBbJxhTxnN4TNFZQQsIrI= =CQXD -----END PGP SIGNATURE----- --=-LbIuD+NSE0mfSgDYZOtG--