Re: kernel: fix hv tools build for arm64 when cross-built

[Wei Liu <wei.liu@kernel.org>]

On Wed, Oct 23, 2024 at 02:01:12PM +0000, Adrian Vladu wrote:
> Hello,
> 
> While trying to build the LIS daemons for Flatcar Container Linux for
> ARM64 (https://www.flatcar.org/), as we are doing Gentoo based
> cross-building from X64 boxes, there was an error while building those
> daemons, because the cross-compile scenario was not working, as ` ARCH
> := $(shell uname -m 2>/dev/null)` always returns `x86_64`.
> 
> I have a working patch for the Linux kernel here that was already
> applied in the Flatcar context and it works:
> https://github.com/flatcar/scripts/blob/94b1df1b19449eb5aa967fd48ba4c1f4a6d5f415/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-sources/files/6.10/z0008-tools-hv-fix-cross-compilation-for-ARM64.patch
> 
> Raw patch link here:
> https://raw.githubusercontent.com/flatcar/scripts/94b1df1b19449eb5aa967fd48ba4c1f4a6d5f415/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-sources/files/6.10/z0008-tools-hv-fix-cross-compilation-for-ARM64.patch
> 
> Sorry for the delivery method via github link, but I cannot send
> proper patches from my work email address currently, as the email
> server does not support it.
> 
> Please let me know if I need to send the patch via the recommended way
> or if the patch can be used directly.
> 
> Also, maybe there is a better way to address the cross-compilation
> issue, I just wanted to report the bug and also provide a possible
> fix.

Saurabh added the ARCH variable. He's CCed.

BTW I think your patch can be simplified by using
  ARCH ?= $(shell uname -m 2>/dev/null)
instead of the ifeq test in your patch.

I don't think that's correct. ARCH will be set to the correct value by
Kbuild. 

Saurabh and Adrian, can you test the following patch?

Thanks,
Wei.

From e6a1827887617c08172e2d0ee0d60549f5ccad65 Mon Sep 17 00:00:00 2001
From: Wei Liu <wei.liu@kernel.org>
Date: Mon, 9 Dec 2024 00:32:50 +0000
Subject: [PATCH] tools/hv: fix cross-compilation issue in hv tools

The Kbuild system sets ARCH to the correct value.

Signed-off-by: Wei Liu <wei.liu@kernel.org>
---
 tools/hv/Makefile | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/hv/Makefile b/tools/hv/Makefile
index 34ffcec264ab..9008223279df 100644
--- a/tools/hv/Makefile
+++ b/tools/hv/Makefile
@@ -2,7 +2,6 @@
 # Makefile for Hyper-V tools
 include ../scripts/Makefile.include
 
-ARCH := $(shell uname -m 2>/dev/null)
 sbindir ?= /usr/sbin
 libexecdir ?= /usr/libexec
 sharedstatedir ?= /var/lib
@@ -20,7 +19,7 @@ override CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include
 override CFLAGS += -Wno-address-of-packed-member
 
 ALL_TARGETS := hv_kvp_daemon hv_vss_daemon
-ifneq ($(ARCH), aarch64)
+ifneq ($(ARCH), arm64)
 ALL_TARGETS += hv_fcopy_uio_daemon
 endif
 ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))
-- 
2.45.2