From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Tue, 8 Jul 2014 14:50:01 +0200 Subject: [RFC PATCH 1/3] arm64: clarify Image header requirement for EFI booting Message-ID: <1404823803-7317-1-git-send-email-ard.biesheuvel@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The 'res5' field in the Image header is defined as 'reserved, should be 0', while it serves a specific purpose when booting via the EFI stub, in which case it should contain the offset of the PE header. So update the doc to reflect this. Signed-off-by: Ard Biesheuvel --- Documentation/arm64/booting.txt | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt index 37fc4f632176..52a07a8d2cfa 100644 --- a/Documentation/arm64/booting.txt +++ b/Documentation/arm64/booting.txt @@ -79,15 +79,15 @@ The decompressed kernel image contains a 64-byte header as follows: u64 res3 = 0; /* reserved */ u64 res4 = 0; /* reserved */ u32 magic = 0x644d5241; /* Magic number, little endian, "ARM\x64" */ - u32 res5 = 0; /* reserved */ + u32 pehdr_offset; /* PE header offset, only used by EFI */ Header notes: - code0/code1 are responsible for branching to stext. - when booting through EFI, code0/code1 are initially skipped. - res5 is an offset to the PE header and the PE header has the EFI - entry point (efi_stub_entry). When the stub has done its work, it + pehdr_offset is an offset to the PE header and the PE header has the + EFI entry point (efi_stub_entry). When the stub has done its work, it jumps to code0 to resume the normal boot process. The image must be placed at the specified offset (currently 0x80000) -- 1.8.3.2