[Pdbg] [PATCH] build: update instructions for hard-float BMCs

[Joel Stanley]

On Wed, 13 Jan 2021 at 05:28, Nicholas Piggin <npiggin at gmail.com> wrote:
>
> The previous patch was papering over the issue, badly. The cause of
> the problem is that some OpenBMC builds have started to use hard float.
> I didn't look hard enough and my ignorance of the ARM environment (and
> the fact it "worked") made me think this was a more benign configuration
> issue.
>
> So update the build instructions to select the hard-float toolchain
> when necessary. Confirmed this works on Debian.
>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>

Reviewed-by: Joel Stanley <joel at jms.id.au>

Thanks for getting to the bottom of this.

> ---
>  README.md | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/README.md b/README.md
> index 7892a8d..e0f4842 100644
> --- a/README.md
> +++ b/README.md
> @@ -17,6 +17,11 @@ top level directory. Static linking is supported and can be performed by adding
>
>  ### Cross compiling for BMC (ARM)
>
> +First, work out if your BMC is using the hard or soft float ABI. If the
> +file /lib/ld-linux.so.3 exists, soft-float. If /lib/ld-linux-armhf.so.3
> +exists, hard-float.
> +
> +To build for soft-float:
>  ```
>  apt-get install gcc-arm-linux-gnueabi
>  ./bootstrap.sh
> @@ -25,11 +30,14 @@ make
>  rsync pdbg root at bmc:/usr/local/bin
>  ```
>
> -Depending on your cross compile environment, you may get a message like
> -`pdbg: No such file or directory` when execting the binary on the BMC,
> -which may be fixable by correcting loader location:
> -
> -`patchelf --set-interpreter /lib/ld-linux-armhf.so.3 pdbg`
> +For hard-float:
> +```
> +apt-get install gcc-arm-linux-gnueabihf
> +./bootstrap.sh
> +./configure --host=arm-linux-gnueabihf CFLAGS="-static"
> +make
> +rsync pdbg root at bmc:/usr/local/bin
> +```
>
>  ## Usage
>
> --
> 2.23.0
>
> --
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