diff options
| -rw-r--r-- | Documentation/arm64/booting.txt | 4 | ||||
| -rw-r--r-- | arch/arm64/mm/init.c | 29 |
2 files changed, 33 insertions, 0 deletions
diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt index 56d6d8b796db..8d0df62c3fe0 100644 --- a/Documentation/arm64/booting.txt +++ b/Documentation/arm64/booting.txt @@ -132,6 +132,10 @@ NOTE: versions prior to v4.6 cannot make use of memory below the physical offset of the Image so it is recommended that the Image be placed as close as possible to the start of system RAM. +If an initrd/initramfs is passed to the kernel at boot, it must reside +entirely within a 1 GB aligned physical memory window of up to 32 GB in +size that fully covers the kernel Image as well. + Any memory described to the kernel (even that below the start of the image) which is not marked as reserved from the kernel (e.g., with a memreserve region in the device tree) will be considered as available to diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 83ae8b5e5666..82ced5fa1e66 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -207,6 +207,35 @@ void __init arm64_memblock_init(void) memblock_add(__pa(_text), (u64)(_end - _text)); } + if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) { + /* + * Add back the memory we just removed if it results in the + * initrd to become inaccessible via the linear mapping. + * Otherwise, this is a no-op + */ + u64 base = initrd_start & PAGE_MASK; + u64 size = PAGE_ALIGN(initrd_end) - base; + + /* + * We can only add back the initrd memory if we don't end up + * with more memory than we can address via the linear mapping. + * It is up to the bootloader to position the kernel and the + * initrd reasonably close to each other (i.e., within 32 GB of + * each other) so that all granule/#levels combinations can + * always access both. + */ + if (WARN(base < memblock_start_of_DRAM() || + base + size > memblock_start_of_DRAM() + + linear_region_size, + "initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) { + initrd_start = 0; + } else { + memblock_remove(base, size); /* clear MEMBLOCK_ flags */ + memblock_add(base, size); + memblock_reserve(base, size); + } + } + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { extern u16 memstart_offset_seed; u64 range = linear_region_size - |