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

[Bin Meng]

Hi Heinrich,

On Thu, Oct 11, 2018 at 11:15 PM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> 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

Pentium does not support 64-bit, so it is expected. In my testing I
always omit the '-cpu' so this is not a problem. But I can document
this.

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

This is due to currently the VGA support is missing in the 64-bit U-Boot.

> 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.

I doubt -enable-kvm works with U-Boot.

>
> 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
>

Will add more info in v2.

Regards,
Bin