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[83.59.163.107]) by smtp.gmail.com with ESMTPSA id e11sm1204629ejz.94.2021.02.03.08.24.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Feb 2021 08:24:44 -0800 (PST) Subject: Re: [PATCH] target/arm: Don't migrate CPUARMState.features To: Aaron Lindsay , qemu-devel@nongnu.org, Peter Maydell References: <20210203161340.55210-1-aaron@os.amperecomputing.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: Date: Wed, 3 Feb 2021 17:24:42 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210203161340.55210-1-aaron@os.amperecomputing.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.539, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.178, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrew Jones , qemu-arm , "Dr . David Alan Gilbert" , Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2/3/21 5:13 PM, Aaron Lindsay wrote: > As feature flags are added or removed, the meanings of bits in the > `features` field can change between QEMU versions, causing migration > failures. Additionally, migrating the field is not useful because it is > a constant function of the CPU being used. Please don't bury patches within mailing list threads. BTW you found yet another 13 years old problem :) 918f5dca18d ("target-arm: Extend feature flags to 64 bits") aa941b94450 ("Savevm/loadvm bits for ARM core, the PXA2xx peripherals and Spitz hardware.") > > Signed-off-by: Aaron Lindsay > Suggested-by: Peter Maydell > --- > target/arm/machine.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/target/arm/machine.c b/target/arm/machine.c > index c9e9fd0a12..7f2511b6ed 100644 > --- a/target/arm/machine.c > +++ b/target/arm/machine.c > @@ -834,7 +834,7 @@ const VMStateDescription vmstate_arm_cpu = { > VMSTATE_UINT64(env.exclusive_addr, ARMCPU), > VMSTATE_UINT64(env.exclusive_val, ARMCPU), > VMSTATE_UINT64(env.exclusive_high, ARMCPU), > - VMSTATE_UINT64(env.features, ARMCPU), > + VMSTATE_UNUSED(sizeof(uint64_t)), > VMSTATE_UINT32(env.exception.syndrome, ARMCPU), > VMSTATE_UINT32(env.exception.fsr, ARMCPU), > VMSTATE_UINT64(env.exception.vaddress, ARMCPU), >