diff options
Diffstat (limited to 'arch/x86/kernel/e820.c')
| -rw-r--r-- | arch/x86/kernel/e820.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 9920122018a0..c3acbd26408b 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -1300,6 +1300,24 @@ void __init e820__memblock_setup(void) } /* + * At this point memblock is only allowed to allocate from memory + * below 1M (aka ISA_END_ADDRESS) up until direct map is completely set + * up in init_mem_mapping(). + * + * KHO kernels are special and use only scratch memory for memblock + * allocations, but memory below 1M is ignored by kernel after early + * boot and cannot be naturally marked as scratch. + * + * To allow allocation of the real-mode trampoline and a few (if any) + * other very early allocations from below 1M forcibly mark the memory + * below 1M as scratch. + * + * After real mode trampoline is allocated, we clear that scratch + * marking. + */ + memblock_mark_kho_scratch(0, SZ_1M); + + /* * 32-bit systems are limited to 4BG of memory even with HIGHMEM and * to even less without it. * Discard memory after max_pfn - the actual limit detected at runtime. |