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Diffstat (limited to 'Documentation/arch/x86')
| -rw-r--r-- | Documentation/arch/x86/index.md | 2 | ||||
| -rw-r--r-- | Documentation/arch/x86/pae.md | 15 |
2 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/arch/x86/index.md b/Documentation/arch/x86/index.md index 3ecb9803a4..73c982385a 100644 --- a/Documentation/arch/x86/index.md +++ b/Documentation/arch/x86/index.md @@ -2,6 +2,8 @@ This section contains documentation about coreboot on x86 architecture. +* [x86 PAE support](pae.md) + ## State of x86_64 support At the moment there's no single board that supports x86_64 or to be exact `ARCH_RAMSTAGE_X86_64` and `ARCH_ROMSTAGE_X86_64`. diff --git a/Documentation/arch/x86/pae.md b/Documentation/arch/x86/pae.md new file mode 100644 index 0000000000..54cd82f2e4 --- /dev/null +++ b/Documentation/arch/x86/pae.md @@ -0,0 +1,15 @@ +# x86_32 PAE documentation + +Due to missing x86_64 support it's required to use PAE enabled x86_32 code. +The corresponding functions can be found in ``src/cpu/x86/pae/``. + +## Memory clearing helper functions + +To clear all DRAM on request of the +[Security API](../../security/memory_clearing.md), a helper function can be used +called `memset_pae`. +The function has additional requirements in contrast to `memset`, and has more +overhead as it uses virtual memory to access memory above 4GiB. +Memory is cleared in 2MiB chunks, which might take a while. + +Make sure to enable caches through MTRRs, otherwise `memset_pae` will be slow! |