[U-Boot] [PATCH 3/4] x86: doc: Mention qemu-x86_64 support

[Heinrich Schuchardt]

On 10/11/2018 03:53 AM, Bin Meng wrote:
> Currently only 32-bit U-Boot for QEMU x86 is documented. Mention
> the 64-bit support.
> 
> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
> ---
> 
>  doc/README.x86 | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/README.x86 b/doc/README.x86
> index 8cc4672..ab48466 100644
> --- a/doc/README.x86
> +++ b/doc/README.x86
> @@ -32,7 +32,7 @@ are supported:
>     - Link (Chromebook Pixel)
>     - Minnowboard MAX
>     - Samus (Chromebook Pixel 2015)
> -   - QEMU x86
> +   - QEMU x86 (32-bit & 64-bit)
>  
>  As for loading an OS, U-Boot supports directly booting a 32-bit or 64-bit
>  Linux kernel as part of a FIT image. It also supports a compressed zImage.
> @@ -376,7 +376,9 @@ QEMU x86 target instructions for bare mode:
>  
>  To build u-boot.rom for QEMU x86 targets, just simply run
>  
> -$ make qemu-x86_defconfig
> +$ make qemu-x86_defconfig (for 32-bit)
> +or
> +$ make qemu-x86_64_defconfig (for 64-bit)
>  $ make all

If your patch series creates a U-Boot usable with QEMU depends on the
chosen CPU:

This one seems to work:
qemu-system-x86_64 -bios u-boot.rom -nographic -cpu core2duo

This one fails (as expected):
qemu-system-x86_64 -bios u-boot.rom --nographic -cpu pentium

I could not get the emulation running without -nographic. Do you know why?

The documentation above is insufficient. Please, provide a minimum QEMU
command line which includes a CPU specification.

I would prefer if you could specify two lines per bitness - one with kvm
and one without, e.g.

qemu-system-x86_64 -bios u-boot.rom -nographic -enable-kvm -cpu host
qemu-system-x86_64 -bios u-boot.rom -nographic -cpu core2duo

qemu-system-i386 -bios u-boot.rom -nographic -enable-kvm -cpu host
qemu-system-i386 -bios u-boot.rom -nographic -cpu core2duo

Best regards

Heinrich

>  
>  Note this default configuration will build a U-Boot for the QEMU x86 i440FX
> @@ -387,6 +389,8 @@ Device Tree Control  --->
>  	...
>  	(qemu-x86_q35) Default Device Tree for DT control
>  
> +To run 64-bit U-Boot, qemu-system-x86_64 should be used instead.
> +
>  Test with coreboot
>  ------------------
>  For testing U-Boot as the coreboot payload, there are things that need be paid
>