arm64: spin-table: add more information in Kconfig help
This feature seems to be sometimes misunderstood. The intention is: [1] Bring the slaves into the U-Boot proper image, not SPL (unless you have a special reason to do otherwise). [2] The operation must be done in a board (SoC) specific manner since how to wake the slaves from the Boot ROM is SoC specific. [3] The slaves must enter U-Boot proper after U-Boot relocates itself because the "cpu-release-addr" property points to the relocated memory area. [2] is already explained in the help. We can make [1] even clearer by mentioning "U-Boot proper" instead of "U-Boot". [3] is missing, so I am adding it to the list. Instead, "before the master CPU jumps to the kernel" is a matter of course, so removed. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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@ -30,8 +30,10 @@ config ARMV8_SPIN_TABLE
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To use this feature, you must do:
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To use this feature, you must do:
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- Specify enable-method = "spin-table" in each CPU node in the
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- Specify enable-method = "spin-table" in each CPU node in the
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Device Tree you are using to boot the kernel
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Device Tree you are using to boot the kernel
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- Let secondary CPUs in U-Boot (in a board specific manner)
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- Bring secondary CPUs into U-Boot proper in a board specific
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before the master CPU jumps to the kernel
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manner. This must be done *after* relocation. Otherwise, the
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secondary CPUs will spin in unprotected memory area because the
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master CPU protects the relocated spin code.
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U-Boot automatically does:
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U-Boot automatically does:
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- Set "cpu-release-addr" property of each CPU node
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- Set "cpu-release-addr" property of each CPU node
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