Re: [U-Boot] [PATCH v3 17/28] x86: Add a way to call 32-bit code from 64-bit mode

On 4 August 2015 at 12:33, Simon Glass sjg@chromium.org wrote:

The procedure to drop from 64-bit mode to 32-bit is a bit messy. Add a function to take care of it. It requires identity-mapped pages and that the calling code is running below 4GB.

Signed-off-by: Simon Glass sjg@chromium.org Reviewed-by: Bin Meng bmeng.cn@gmail.com

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Changes in v3: None Changes in v2:

• Add a comment about the REX prefix
• Drop the REX prefix in 32-bit mode

arch/x86/cpu/Makefile | 6 +++++ arch/x86/cpu/call32.S | 64 ++++++++++++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/cpu.h | 9 +++++++ 3 files changed, 79 insertions(+) create mode 100644 arch/x86/cpu/call32.S

Applied to u-boot-x86.