Re: [edk2-platforms][PATCH] Readme.md: Update cross compiling section

["Leif Lindholm" <leif@nuviainc.com>]

Hi Vin Xue,

If the documentation can be improved, it should.

I will propose an update to the cross-compilation section, thank you
for reporting that the link had stopped working.

On Wed, Jul 15, 2020 at 10:31:23 +0000, Vin Xue wrote:
> Hi Lindholm,
> 
> Thanks for your comments.
> Usually, I am working on Windows PC for BIOS development.
> Today I tried to build edk2-platform AAarch64 code, and found it's not
> easy to follow readme document. So, I submitted the patch.
> 
> Please drop the patch if there is a better update in the near future.
> 
> >  ### clang
> >  Clang does not require separate cross compilers, but it does need a
> > @@ -160,6 +163,9 @@ variable `{TOOL_CHAIN_TAG}_{TARGET_ARCH}_PREFIX` - in the case above,
> >  **GCC5_AARCH64_PREFIX**.
> >
> >  So, referring to the cross compiler toolchain table above, we should prepend the `build` command line with `GCC5_AARCH64_PREFIX=aarch64-linux-gnu-`.
> > +```
> > +$ GCC5_AARCH64_PREFIX=aarch64-linux-gnu- build -n $NUM_CPUS -a AARCH64 -t GCC5 -p Platform/ARM/JunoPkg/ArmJuno.dsc
> > +```

Actually, I misread this hunk since the context line before the
addition is too long, wrapping unfortuinately in my email client; I
read it as *replacing* the variable setting with the full usage
example. Apologies for this.
I have no objection to the addition of the full usage example. I will
drop the other bits of this patch and send out a minor set of readme
updates including the remainder of this patch.

/
    Leif

> 
> How to build a platform is already described in the section
> immediately preceding this one. This paragraph tells you how to inform
> the build system to apply a prefix for the compiler if cross compiling.
> 
> Seprate note (to self, really): we don't need the -n thing anymore,
> the 'build' command has been updated to figure this out for itself.
> 
> /
>     Leif
> 
> >
> >  ## Using uefi-tools helper scripts
> >  uefi-tools is a completely unofficial set of helper-scripts developed by Linaro.
> > --
> > 2.27.0.windows.1
> >