QCLINUX: qcom.config: Enable 39-bit VA space for 4K-page builds#558
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Komal-Bajaj merged 1 commit intoqualcomm-linux:tech/all/configfrom Jan 28, 2026
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| 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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Thanks @shashim-quic . Updated qcom.config and changed commit. Please approve.
Thanks,
Anurag
For Qualcomm 4K-page based builds, explicitly enable VA_BITS_39 in the qcom.config fragment. 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. Selecting 39-bit VA sizing aligns better with constraints and performance characteristics of lower-end Qualcomm platforms. 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 <[email protected]>
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For Qualcomm 4K-page based builds, explicitly enable VA_BITS_39
in the qcom.config fragment.
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.
Selecting 39-bit VA sizing aligns better with constraints and performance
characteristics of lower-end Qualcomm platforms.
This change does not affect 64K-page builds (which retain 48/52-bit VA).
Background:
kernels must be able to fall back to 48-bit at boot.