QCLINUX: arm64: Kconfig: default to 39-bit VAs for 4K-page builds #558
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Lower-end arm64 systems typically do not benefit from a 48/52-bit VA space, while they do benefit from smaller page tables and reduced TLB pressure. Make 39-bit the default for 4K-page builds (3-level tables). This change does not affect 64K-page builds (which retain 48/52-bit VA). Background: - With 4K pages, arm64 supports 39-bit (3-level) or 48-bit (4-level) VAs. - 52-bit VAs are only available with 64K pages and ARMv8.2-LVA, and kernels must be able to fall back to 48-bit at boot. Signed-off-by: Anurag Pateriya <apateriy@qti.qualcomm.com>
| choice | ||
| prompt "Virtual address space size" | ||
| # Prefer smaller VA (3-level tables) on 4K-page builds | ||
| default ARM64_VA_BITS_39 if PAGE_SIZE_4KB |
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Let's update qcom.config instead of changing upstream code.
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Lower-end arm64 systems typically do not benefit from a 48/52-bit VA space, while they do benefit from smaller page tables and reduced TLB pressure. Make 39-bit the default for 4K-page builds (3-level tables).
This change does not affect 64K-page builds (which retain 48/52-bit VA).
Background: