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b=myIPT7kzsvwaEphWZRI8htKvnmkYB3X5dx43Zdq+bIvS+Orrp7m6OAqjbL5caUD+Do lOt0qZPnZSsWLw+6BQZpYUkqRq8quXORu6jLorj1ZxlgYm34Tb4eVfbFnygslvOM2aSf +1PkmwSbinEoW47nSbKd3j7Lm3vruQgspJoBMdb6ApPHsxswBQgJpYUvrAF7T5NTJMb2 ddAW8xPITEEvCaT09OQ6DeFoCF4AT8XHHt3cMJDXYhDvm6imWMV0a+b960gA+qyVD6Yz mJpRpQROhLLOuELYdfRN5sHzeq0LjvdgJi7oxfe4YckbUyHOMTF0RFfQLt4NMb0jT/bP S2/g== X-Forwarded-Encrypted: i=1; AKwUvBx02Yvyh7+KTjRW/qfa4DdfxxEUNerUCO/5FKzmWolNfBbmW485f177Lbynea4hM1Le+1i5qqol+g==@kvack.org X-Gm-Message-State: AFuF++ko1hti9sH3ZHIvcw4b/u12nXEQ6K4m0in/9Qao7PGcav08a/mL geWZm2MhFhxJOxaaOUlrr+8W4odtLJ+ewBeVrpw+iqoUc2o37SM2py7HkDVSt+fHqm8hRZvtkr9 VqR/3TA== X-Received: from pgdh15.prod.google.com ([2002:a05:6a02:518f:b0:cc4:3b8d:ea37]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:22d4:b0:857:73e2:9103 with SMTP id d2e1a72fcca58-86b336d6a0bmr1513199b3a.19.1789080156858; Thu, 10 Sep 2026 15:42:36 -0700 (PDT) Date: Thu, 10 Sep 2026 15:42:36 -0700 In-Reply-To: <20260910221832.GH3968357@nvidia.com> Mime-Version: 1.0 References: <20260903023452.721732-1-loganodell@google.com> <20260904160009.GV4157646@nvidia.com> <20260905012403.GX4157646@nvidia.com> <20260910143448.GD3968357@nvidia.com> <20260910171210.GF3968357@nvidia.com> <20260910221832.GH3968357@nvidia.com> Message-ID: Subject: Re: [RFC PATCH 0/3] liveupdate: Move to feature flags for LUO and memfd ABI compatibility From: Sean Christopherson To: Jason Gunthorpe Cc: David Matlack , Logan Odell , arnd@arndb.de, pasha.tatashin@soleen.com, rppt@kernel.org, pratyush@kernel.org, graf@amazon.com, akpm@linux-foundation.org, pbonzini@redhat.com, maz@kernel.org, oupton@kernel.org, bhelgaas@google.com, alex@shazbot.org, kevin.tian@intel.com, dwmw2@infradead.org, baolu.lu@linux.intel.com, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-pci@vger.kernel.org, iommu@lists.linux.dev Content-Type: text/plain; charset="us-ascii" X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 8BF3740003 X-Stat-Signature: 5msi6xqjuderpat98x6jrshgfc3m9z9j X-HE-Tag: 1789080158-545388 X-HE-Meta: U2FsdGVkX1+v/Miow7GBuwYGOuF0b8nGzYUEy8xqHZQu0tuFGYkGMzqrUDiKxw81oiiUXQVhK5XWZA/Koh2P26OKhqhPjZdWjf1Dx/YmFYuZ+fURxkg2GptW1G12Cr4LaHvMirop/MO2iMbZHewjqvkiIvPEVUf4lHF2n00VVfup7WMan1Oadb27rEmWVjyF4rK9Po91t6rR7zbvCLIyATapqNWq1dFSTVxBkZE9khN9M5wwejwdevJe/TndZx+vE/kT/KckHaKjtE2ynkahSJtWf9k46P0mRTphyhA6XTLcaupKyc3kv2toauBEsMTM2siRD54QO1upG8cvCZ9cKuV2If4wqrONlZKgHYFkAuR/FuDczdsAvd+Mxw6nc6L1NWL+b1OSu/OqhRE+jbBHWTLYJbi9V+XwsmA/V3CBat+ZrQbQc2CgcuM/iFzQXDeIDjZ18f55nQvObvPX6E5ojIXmeQBYOEO33hJ1pSKHISTuZe36NVDOWQgyfS8zwt+TLC4dR+CDCDBmR4xJjC1LZ2Il2zg21DWR7wSHSr1yU17fk9tYzEsIHDqImcrOT4wykAKc2j2iL93iYKHjOneYeBj7Q3tOaxQsNp8AY788qj0TuPPZSZwubeYRe6SE0ipLjXLmEFniOd8VqRdGbukz6gmD7wiIWbCpqQG6FEng2P7J1O8GgP1pXw+hF3l1pZ53cq4zLog6t6AU0DukNCRTXOQqLxZvz4kscPQxfgNuWESQrHU0oLo4oXIpAm9S8rY/4/3guLZZTPuJxbQNI2rmJRveYLSoDYtO4yAc/YQDJT12nYFRxPzPqS1l726g4DW3JCcpXr0mES4N5K2fGnCfIoKzVE9U46pEHxM0FcsFAheRK0ZSOFegdS6wGF+78jOJBZezygcXp/09gbyKkl3lM66tsL2W33Isz4lGM2uGyAMX7BbRpAIegzUpbGpRJFE7COGOZZ3fzIrgLGvAyvs mVFAn/k0 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Sep 10, 2026, Jason Gunthorpe wrote: > Sean's initial email was asking for strict never-break ABI compatability > rules on top, and that is what I've been reacting to. No, I was never asking for that. I think we just have a different interpretation of ABI, or rather are talking about different pieces of ABI. I am still asking for never-break serialization format compatibility, i.e. the more literal save/restore ABI. I'm not asking for full backwards/forwards compatibility across all kernels version, i.e. the higher level "kernel" ABI. To phrase things differently: I am a-ok if kernels are inherently incompatible because they fundamentally operate differently and/or support different features. I am not ok if we end up with incompatible kernels because the save/restore interfaces and payloads are poorly designed, lack abstraction, etc.