From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Fri, 16 Oct 2020 11:36:38 +0800
From: Fino Meng <fino.meng@linux.intel.com>
Subject: Re: build scripts for the WIP xenomai porting to kernel 5.4
Message-ID: <20201016033638.GB5581@linux.intel.com>
References: <20201014132459.GB24671@linux.intel.com>
 <8e59bc35-84ae-78be-8296-4f2367e8e844@siemens.com>
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To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: xenomai@xenomai.org

On Thu, Oct 15, 2020 at 04:20:11PM +0200, Jan Kiszka wrote:
> On 14.10.20 15:25, Fino Meng wrote:
> > hi team,
> > 
> > I just updated the scripts to build the WIP version xenomai porting to
> > kernel 5.4, just follow the steps:
> > 
> > git clone https://github.com/finomeng/xenomai-mirror.git /tmp/xenomai-mirror.next-5.4
> > cd /tmp/xenomai-mirror.next-5.4
> > git checkout -t origin/wip/next-5.4-porting
> > 
> > git clone https://github.com/intel/linux-stable-xenomai /tmp/kernel
> > cd /tmp/kernel
> > git checkout -t review/5.4.59/stable/ipipe-x86
> > 
> > ./patching-xenomai2kernel.sh
> > 
> > cp config_xenomai.kernel_debug .config
> > make olddefconfig
> > ./build-debpkg.sh
> > 
> > 
> > I didn't put it togethter with ISAR/Debian yet. I test it with a PC with Debian 10 installed.
> > 
> > if no error, linux-image-*.deb and linux-headers-*.deb should generated outside kernel folder,
> > copy them to your target test device with already installed a Debian/Ubuntu,
> > install the deb with "dpkg -i", update-grub should be called during install linux-image-*.deb
> > reboot and select to boot the new kernel in grub's menu
> > 
> > the build steps also written in patching-xenomai2kernel.sh and build-debpkg.sh
> > 
> > switchtest will fail in current version, for example: "./switchtest rtk_fp_ufpp0"
> > will print:
> > 
> > r0: 2147483648 != 1000
> > r1: 2147483648 != 1000
> > r2: 2147483648 != 1000
> > r3: 2147483648 != 1000
> > r4: 2147483648 != 1000
> > r5: 2147483648 != 1000
> > r6: 2147483648 != 1000
> > r7: 2147483648 != 1000
> > ymm0: 2676586395008836901/0 != 1000/1000
> > ymm1: 71776119061217280/0 != 1000/1000
> > ymm2: 0/0 != 1000/1000
> > ymm3: 1000/0 != 1000/1000
> > ymm4: 1000/0 != 1000/1000
> > ymm5: 1000/0 != 1000/1000
> > ymm6: 1000/0 != 1000/1000
> > ymm7: 1000/0 != 1000/1000
> > Error after context switch from task 1(rtk_fp_ufpp0-1) to task 0(sleeper_ufps0-0),
> > FPU registers were set to 0 (maybe task sleeper_ufps0-0)
> > 
> > if meet more questions just write to me, thanks!
> > 
> > BR fino
> > 
> 
> I can reproduce in KVM and poked around a bit, though without finding
> the needle yet. Likely, there are multiple aspects. The change in
> upstream to FPU switching on user-return is a hot lead, but it takes a
> bit to fully grasp that and map it on our scenarios with Xenomai.
> 
> Jan

it seems that, switch_fpu_prepare() and switch_fpu_finish() are
for kernel thread context switch (in __switch_to() )and switch_fpu_return() is needed
before return to userspace( in prepare_exit_to_usermode()).

BR fino

> 
> -- 
> Siemens AG, T RDA IOT
> Corporate Competence Center Embedded Linux