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

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

[Adrian Vladu]

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.

Thank you,
Adrian Vladu

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

[Wei Liu]

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

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

[Saurabh Singh Sengar]

On Mon, Dec 09, 2024 at 12:44:22AM +0000, Wei Liu wrote:
> 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.

Agree, this is better way to handle it.

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

If we build locally on ARM64, there is a chance that ARCH may not be set,
leading to build failures for arm64. IMO we should provide a fallback
option for local builds when ARCH is not set.

> 
> 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)

My understanding is ARCH could be either aarch64 or arm64.

- Saurabh

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

[Wei Liu]

On Mon, Dec 09, 2024 at 12:30:35AM -0800, Saurabh Singh Sengar wrote:
> On Mon, Dec 09, 2024 at 12:44:22AM +0000, Wei Liu wrote:
> > 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.
> 
> Agree, this is better way to handle it.
> 
> > 
> > I don't think that's correct. ARCH will be set to the correct value by
> > Kbuild. 
> 
> If we build locally on ARM64, there is a chance that ARCH may not be set,
> leading to build failures for arm64. IMO we should provide a fallback
> option for local builds when ARCH is not set.

How do you build locally? Even if you build those tools in tools/hv, it
still uses the Kbuild system, which sets ARCH to the correct value,
right?

Thanks,
Wei.

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

[Saurabh Singh Sengar]

On Mon, Dec 09, 2024 at 06:46:42PM +0000, Wei Liu wrote:
> On Mon, Dec 09, 2024 at 12:30:35AM -0800, Saurabh Singh Sengar wrote:
> > On Mon, Dec 09, 2024 at 12:44:22AM +0000, Wei Liu wrote:
> > > 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.
> > 
> > Agree, this is better way to handle it.
> > 
> > > 
> > > I don't think that's correct. ARCH will be set to the correct value by
> > > Kbuild. 
> > 
> > If we build locally on ARM64, there is a chance that ARCH may not be set,
> > leading to build failures for arm64. IMO we should provide a fallback
> > option for local builds when ARCH is not set.
> 
> How do you build locally? Even if you build those tools in tools/hv, it
> still uses the Kbuild system, which sets ARCH to the correct value,
> right?
> 

I have tested your patch in ARM64 VM, can see the build failure. Here's the
exact details how I tested:


azureuser@ARM64-ubunutu24:/work/linux-next$ cd tools/hv/
azureuser@ARM64-ubunutu24:/work/linux-next/tools/hv$ make
make[1]: Entering directory '/work/linux-next/tools/hv'
  CC      hv_kvp_daemon.o
  LD      hv_kvp_daemon-in.o
make[1]: Leaving directory '/work/linux-next/tools/hv'
  LINK    hv_kvp_daemon
make[1]: Entering directory '/work/linux-next/tools/hv'
  CC      hv_vss_daemon.o
  LD      hv_vss_daemon-in.o
make[1]: Leaving directory '/work/linux-next/tools/hv'
  LINK    hv_vss_daemon
make[1]: Entering directory '/work/linux-next/tools/hv'
  CC      hv_fcopy_uio_daemon.o
  CC      vmbus_bufring.o
vmbus_bufring.c:11:10: fatal error: emmintrin.h: No such file or directory
   11 | #include <emmintrin.h>
      |          ^~~~~~~~~~~~~
compilation terminated.
make[1]: *** [/work/linux-next/tools/build/Makefile.build:106: vmbus_bufring.o] Error 1
make[1]: Leaving directory '/work/linux-next/tools/hv'
make: *** [Makefile:48: hv_fcopy_uio_daemon-in.o] Error 2
azureuser@ARM64-ubunutu24:/work/linux-next/tools/hv$ uname -a
Linux ARM64-ubunutu24 6.12.0-next-20241128+ #12 SMP Fri Nov 29 14:53:06 UTC 2024 aarch64 aarch64 aarch64 GNU/Linux

- Saurabh

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

[Wei Liu]

On Mon, Dec 09, 2024 at 07:39:10PM -0800, Saurabh Singh Sengar wrote:
> On Mon, Dec 09, 2024 at 06:46:42PM +0000, Wei Liu wrote:
> > On Mon, Dec 09, 2024 at 12:30:35AM -0800, Saurabh Singh Sengar wrote:
> > > On Mon, Dec 09, 2024 at 12:44:22AM +0000, Wei Liu wrote:
> > > > 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 ?= $(shell uname -m 2>/dev/null)
> > > > instead of the ifeq test in your patch.
> > > 
> > > Agree, this is better way to handle it.
> > > 
> > > > 
> > > > I don't think that's correct. ARCH will be set to the correct value by
> > > > Kbuild. 
> > > 
> > > If we build locally on ARM64, there is a chance that ARCH may not be set,
> > > leading to build failures for arm64. IMO we should provide a fallback
> > > option for local builds when ARCH is not set.
> > 
> > How do you build locally? Even if you build those tools in tools/hv, it
> > still uses the Kbuild system, which sets ARCH to the correct value,
> > right?
> > 
> 
> I have tested your patch in ARM64 VM, can see the build failure. Here's the
> exact details how I tested:
> 
> 
> azureuser@ARM64-ubunutu24:/work/linux-next$ cd tools/hv/
> azureuser@ARM64-ubunutu24:/work/linux-next/tools/hv$ make
> make[1]: Entering directory '/work/linux-next/tools/hv'
>   CC      hv_kvp_daemon.o
>   LD      hv_kvp_daemon-in.o
> make[1]: Leaving directory '/work/linux-next/tools/hv'
>   LINK    hv_kvp_daemon
> make[1]: Entering directory '/work/linux-next/tools/hv'
>   CC      hv_vss_daemon.o
>   LD      hv_vss_daemon-in.o
> make[1]: Leaving directory '/work/linux-next/tools/hv'
>   LINK    hv_vss_daemon
> make[1]: Entering directory '/work/linux-next/tools/hv'
>   CC      hv_fcopy_uio_daemon.o
>   CC      vmbus_bufring.o
> vmbus_bufring.c:11:10: fatal error: emmintrin.h: No such file or directory
>    11 | #include <emmintrin.h>
>       |          ^~~~~~~~~~~~~

I see. I create an arm64 VM and reproduce the issue. The ARCH variable
is not set.

That said, the build breaks because emmintrin.h is not available on
arm64. It is only needed for _mm_pause().  There is maybe an
architecture specific header file we can use to make it build.

Thanks,
Wei.

> compilation terminated.
> make[1]: *** [/work/linux-next/tools/build/Makefile.build:106: vmbus_bufring.o] Error 1
> make[1]: Leaving directory '/work/linux-next/tools/hv'
> make: *** [Makefile:48: hv_fcopy_uio_daemon-in.o] Error 2
> azureuser@ARM64-ubunutu24:/work/linux-next/tools/hv$ uname -a
> Linux ARM64-ubunutu24 6.12.0-next-20241128+ #12 SMP Fri Nov 29 14:53:06 UTC 2024 aarch64 aarch64 aarch64 GNU/Linux
> 
> - Saurabh

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

[Wei Liu]

On Tue, Dec 10, 2024 at 06:34:28PM +0000, Wei Liu wrote:
> On Mon, Dec 09, 2024 at 07:39:10PM -0800, Saurabh Singh Sengar wrote:
> > On Mon, Dec 09, 2024 at 06:46:42PM +0000, Wei Liu wrote:
> > > On Mon, Dec 09, 2024 at 12:30:35AM -0800, Saurabh Singh Sengar wrote:
> > > > On Mon, Dec 09, 2024 at 12:44:22AM +0000, Wei Liu wrote:
> > > > > 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 ?= $(shell uname -m 2>/dev/null)
> > > > > instead of the ifeq test in your patch.
> > > > 
> > > > Agree, this is better way to handle it.
> > > > 
> > > > > 
> > > > > I don't think that's correct. ARCH will be set to the correct value by
> > > > > Kbuild. 
> > > > 
> > > > If we build locally on ARM64, there is a chance that ARCH may not be set,
> > > > leading to build failures for arm64. IMO we should provide a fallback
> > > > option for local builds when ARCH is not set.
> > > 
> > > How do you build locally? Even if you build those tools in tools/hv, it
> > > still uses the Kbuild system, which sets ARCH to the correct value,
> > > right?
> > > 
> > 
> > I have tested your patch in ARM64 VM, can see the build failure. Here's the
> > exact details how I tested:
> > 
> > 
> > azureuser@ARM64-ubunutu24:/work/linux-next$ cd tools/hv/
> > azureuser@ARM64-ubunutu24:/work/linux-next/tools/hv$ make
> > make[1]: Entering directory '/work/linux-next/tools/hv'
> >   CC      hv_kvp_daemon.o
> >   LD      hv_kvp_daemon-in.o
> > make[1]: Leaving directory '/work/linux-next/tools/hv'
> >   LINK    hv_kvp_daemon
> > make[1]: Entering directory '/work/linux-next/tools/hv'
> >   CC      hv_vss_daemon.o
> >   LD      hv_vss_daemon-in.o
> > make[1]: Leaving directory '/work/linux-next/tools/hv'
> >   LINK    hv_vss_daemon
> > make[1]: Entering directory '/work/linux-next/tools/hv'
> >   CC      hv_fcopy_uio_daemon.o
> >   CC      vmbus_bufring.o
> > vmbus_bufring.c:11:10: fatal error: emmintrin.h: No such file or directory
> >    11 | #include <emmintrin.h>
> >       |          ^~~~~~~~~~~~~
> 
> I see. I create an arm64 VM and reproduce the issue. The ARCH variable
> is not set.
> 
> That said, the build breaks because emmintrin.h is not available on
> arm64. It is only needed for _mm_pause().  There is maybe an
> architecture specific header file we can use to make it build.

Never mind. There are also open coded x86 assembly code in
vmbus_bufring.c. Let's fix the cross-compilation issue first.

Thanks,
Wei.

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

[Saurabh Singh Sengar]

On Tue, Dec 10, 2024 at 07:07:37PM +0000, Wei Liu wrote:
> On Tue, Dec 10, 2024 at 06:34:28PM +0000, Wei Liu wrote:
> > On Mon, Dec 09, 2024 at 07:39:10PM -0800, Saurabh Singh Sengar wrote:
> > > On Mon, Dec 09, 2024 at 06:46:42PM +0000, Wei Liu wrote:
> > > > On Mon, Dec 09, 2024 at 12:30:35AM -0800, Saurabh Singh Sengar wrote:
> > > > > On Mon, Dec 09, 2024 at 12:44:22AM +0000, Wei Liu wrote:
> > > > > > 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 ?= $(shell uname -m 2>/dev/null)
> > > > > > instead of the ifeq test in your patch.
> > > > > 
> > > > > Agree, this is better way to handle it.
> > > > > 
> > > > > > 
> > > > > > I don't think that's correct. ARCH will be set to the correct value by
> > > > > > Kbuild. 
> > > > > 
> > > > > If we build locally on ARM64, there is a chance that ARCH may not be set,
> > > > > leading to build failures for arm64. IMO we should provide a fallback
> > > > > option for local builds when ARCH is not set.
> > > > 
> > > > How do you build locally? Even if you build those tools in tools/hv, it
> > > > still uses the Kbuild system, which sets ARCH to the correct value,
> > > > right?
> > > > 
> > > 
> > > I have tested your patch in ARM64 VM, can see the build failure. Here's the
> > > exact details how I tested:
> > > 
> > > 
> > > azureuser@ARM64-ubunutu24:/work/linux-next$ cd tools/hv/
> > > azureuser@ARM64-ubunutu24:/work/linux-next/tools/hv$ make
> > > make[1]: Entering directory '/work/linux-next/tools/hv'
> > >   CC      hv_kvp_daemon.o
> > >   LD      hv_kvp_daemon-in.o
> > > make[1]: Leaving directory '/work/linux-next/tools/hv'
> > >   LINK    hv_kvp_daemon
> > > make[1]: Entering directory '/work/linux-next/tools/hv'
> > >   CC      hv_vss_daemon.o
> > >   LD      hv_vss_daemon-in.o
> > > make[1]: Leaving directory '/work/linux-next/tools/hv'
> > >   LINK    hv_vss_daemon
> > > make[1]: Entering directory '/work/linux-next/tools/hv'
> > >   CC      hv_fcopy_uio_daemon.o
> > >   CC      vmbus_bufring.o
> > > vmbus_bufring.c:11:10: fatal error: emmintrin.h: No such file or directory
> > >    11 | #include <emmintrin.h>
> > >       |          ^~~~~~~~~~~~~
> > 
> > I see. I create an arm64 VM and reproduce the issue. The ARCH variable
> > is not set.
> > 
> > That said, the build breaks because emmintrin.h is not available on
> > arm64. It is only needed for _mm_pause().  There is maybe an
> > architecture specific header file we can use to make it build.
> 
> Never mind. There are also open coded x86 assembly code in
> vmbus_bufring.c. Let's fix the cross-compilation issue first.

sent a patch for this : https://lkml.org/lkml/2024/12/12/307

- Saurabh

> 
> Thanks,
> Wei.