Re: [Xen-devel] [PATCH for-4.8] stubdom: make GMP aware that it's being cross-compiled

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Oct 31, 2016 at 02:57:54AM -0600, Jan Beulich wrote:
> >>> On 29.10.16 at 19:22, <wei.liu2@xxxxxxxxxx> wrote:
> > Append --build and --host flags to GMP's configure script so that it
> > knows it is being compiled for another architecture.
> 
> Why --host and --build? Aiui,
> - host is where the configure runs,
> - build is where tool chain components being built are supposed to run,
> - target is where the final binaries are intended to run.

I think you got them wrong, in particular host and build semantics.

build is where the build runs, host is where the resulting binary runs,
target is where the output of the resulting binary runs (assuming the
binary is compiler).

https://www.gnu.org/software/autoconf/manual/autoconf-2.65/html_node/Specifying-Target-Triplets.html

Since GMP is not a compiler, target is not relevant here.

> 
> We're talking about a simple cross build here afaict, not a Canadian
> cross,

Correct, it's a simple cross build, not a Canadian cross.

The rest is moot because it is based on wrong assumption.

Wei.

> i.e. host == build, with only target being different, i.e. I'd
> assume you really want to specify --target (and leave host and build
> to be determined automatically), along the lines of e.g. a simple
> compiler cross build, which produces
> 
> S["target_os"]="linux-gnu"
> S["target_vendor"]="pc"
> S["target_cpu"]="x86_64"
> S["target"]="x86_64-pc-linux-gnu"
> 
> S["host_os"]="linux-gnu"
> S["host_vendor"]="pc"
> S["host_cpu"]="i686"
> S["host"]="i686-pc-linux-gnu"
> 
> S["build_os"]="linux-gnu"
> S["build_vendor"]="pc"
> S["build_cpu"]="i686"
> S["build"]="i686-pc-linux-gnu"
> 
> among its awk expression to perform substitution in various other
> files/scripts (except that in the stubdom case it would be target_os
> to be different from host_os/build_os, and - on a 64-bit system -
> target_cpu matching host_cpu/build_cpu).
> 
> Jan
> 

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