Bug#834505: arm64 boot failure with large physical memory range
Package: linux
Version: 4.6.4-1
X-Debbugs-CC: steve@einval.com, wookey@wookware.org, zheng.xu@linaro.org
Upstream commit 211102d85 ("arm64: defconfig: enable 48-bit virtual
addresses") changed the default configuration for arm64 to be 48-bit
VA (CONFIG_ARM64_VA_BITS_48). This is required in order to be able to
access the full amount of RAM available on some current arm64 systems
(currently with large memory holes, but could apply to any system with
>512GB of RAM). Without this, on these systems, the kernel will fail
to access the initrd, which will have been located near top of RAM by
GRUB. Error message given is:
---
initrd not fully accessible via the linear mapping -- please check
your bootloader ...
---
So please enable CONFIG_ARM64_VA_BITS_48 for arm64 kernels.
Note: this change _will_ cause breakage in certain userland software
making non-portable assumptions about available of top address bits
for pointer tagging - including luajit and mozilla-js (and hence
everything using mozilla-js).
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