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([2a05:6e02:1041:c10:8e86:6bca:4a7e:8b62]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-493eb6ea082sm62035225e9.11.2026.07.09.06.00.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Jul 2026 06:00:24 -0700 (PDT) Message-ID: <6585df3f-2d4e-43b0-81cc-72195a5ceac7@oss.qualcomm.com> Date: Thu, 9 Jul 2026 15:00:23 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] arm64: Disallow disabling boot CPU based on config To: Sudeep Holla Cc: Sneh Mankad , Thomas Gleixner , Peter Zijlstra , "Rafael J. Wysocki" , Pavel Machek , Len Brown , Catalin Marinas , Mark Rutland , Lorenzo Pieralisi , Will Deacon , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Maulik Shah References: <20260703-disable_boot_cpu_offline-v2-1-782d16ff58c3@oss.qualcomm.com> <20260703-competent-adaptable-coot-f8daaf@sudeepholla> <4b7fe7e6-2531-4d26-9085-43f40a2ce2e0@oss.qualcomm.com> <20260706-practical-inchworm-of-experience-d4e0ed@sudeepholla> Content-Language: en-US From: Daniel Lezcano In-Reply-To: <20260706-practical-inchworm-of-experience-d4e0ed@sudeepholla> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Info: AW1haW4tMjYwNzA5MDEyNyBTYWx0ZWRfX/Zi5TwVr3lsS GSSdAhkvgeVJ6K0CP0DBnWYbz2wMkHxEQShyRUmgm01mEcBftf+zYallKae8wDgeCDyNrfvQHlK I3qg+V/fa5JU8Gr7ZdBmkmjcuup8m9g= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzA5MDEyNyBTYWx0ZWRfX/biZv6J5CLpP 9vRzOJTOrTiNQlrZ/wjoDDJiLRN7b18r91bocIcJjVYJriAtkUNqFpOcQyxqzxvepVsYW4UQu6p R8ZuyJBKYLRaQla7F4cx1JJf5nfNqPxquGbQ+hxveF6bEa8w8FYFhmgtZZD6v4la+waJKMaSZ2W 6GBzJODAKXMu7pKcldMDcRwAQRoEDerxljqumbWk1CTKr4KG1u4W0+cApL2blQAXAmFpF/lGTdE x2/J2LyeWtC0o5SioRJrZbxwC6JCH+00Es1fCjP2p8UymSvwMW0DaVk1s8FquTfXhndRvFXEmaF rzDpNZpvgPRJkwVl6BSrv0oNNXepKMql7XiZRpU5UMEQJZIWpz1L5huiOwa99cn2vWpVjZM3FvI w+HUFO0yi+vXIzQsymG8fLDsIdXf9+AX/SIOJdNTZiu11NqVzaXANR4lR+MaZ8tD6CVMN1vFLjE V3zA1kTAcUE1TlG5LKA== X-Proofpoint-GUID: WWoz6U7ACLSmuOssG9j7hKDoYWmUizhy X-Proofpoint-ORIG-GUID: WWoz6U7ACLSmuOssG9j7hKDoYWmUizhy X-Authority-Analysis: v=2.4 cv=QoVuG1yd c=1 sm=1 tr=0 ts=6a4f9b70 cx=c_pps a=oc9J++0uMp73DTRD5QyR2A==:117 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=YMgV9FUhrdKAYTUUvYB2:22 a=OGcXQ3cJPyzbm-w1UIMA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=iYH6xdkBrDN1Jqds4HTS:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-09_02,2026-07-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 priorityscore=1501 adultscore=0 suspectscore=0 lowpriorityscore=0 clxscore=1015 bulkscore=0 phishscore=0 malwarescore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607090127 [ Cc'ed Maulik ] On 7/6/26 11:16, Sudeep Holla wrote: > On Sat, Jul 04, 2026 at 08:43:39AM +0200, Daniel Lezcano wrote: >> >> Hi Sudeep, >> >> Le 03/07/2026 à 17:51, Sudeep Holla a écrit : >>> (It is always good to cc all PSCI maintainer for any ARM64 CPU >>> hotpug/suspend related changes) >>> >>> On Fri, Jul 03, 2026 at 04:50:02PM +0530, Sneh Mankad wrote: >>>> The Qualcomm SoCs like LeMans, Monaco support suspend to ram which leads >>>> the SoC to ACPI S3 similar state where SoC is turned off and DDR is >>>> retained. The hardware design on these SoCs forces a constraint to suspend >>>> and resume the system on boot CPU / CPU0. >>>> >>> And you fail to explain why they have that constraint. >>> > > I still need the above to understand the issue/constraint better. Ok, I think Maulik can give some details here. >>> Is it because some secure context is not allowed to migrate ? >>> >>> We already have a mechanism for that in place and this hack is not at all >>> required. >> Do you mean a mechanism for the secure context or for preventing CPU0 ? >> > > I meant constraint based on secure context. >