smp: Allow switching the boot (primary) CPU core#563
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jannau wants to merge 3 commits intoAsahiLinux:mainfrom
Open
smp: Allow switching the boot (primary) CPU core#563jannau wants to merge 3 commits intoAsahiLinux:mainfrom
jannau wants to merge 3 commits intoAsahiLinux:mainfrom
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jannau
commented
Apr 16, 2026
jannau
commented
It will be used to switch to CPU 0 on M3 and later to avoid confusion when Linux is not started with CPU 0. Signed-off-by: Janne Grunau <j@jannau.net>
yuyuyureka
reviewed
Apr 17, 2026
M3 and later Apple silicon SoCs start m1n1 on the first perfomance core. The cluster layout remained unchanged with an efficiency core cluster first. This causes an annoying but mostly cosmetic issue in Linux. Linux assigns CPU index 0 to the boot CPU. This results in a mismatch of logical and physical CPU core order. As seen with the Radxa Orion O6 this will at least generate support questions but is also annoying for CPU pinning. It's likely to result in pinning to mixture of performance and efficiency cores. While functionality it should not matter to which secondary CPU core control is passed the only expected use case is switching to CPU core 0. Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Janne Grunau <j@jannau.net>
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I've seen now some unhandled exceptions after switching the boot CPU during DT preparation so it's possible that there is something missing during initialisation of the new boot CPU |
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