[PATCH u-boot v2.1 38/38] ARM: enable LTO for some boards

Marek Behun marek.behun at nic.cz
Mon Mar 15 10:42:31 CET 2021 

On Fri, 12 Mar 2021 15:47:12 -0500
Tom Rini <trini at konsulko.com> wrote:

> On Fri, Mar 12, 2021 at 06:36:05PM +0100, Marek Behun wrote:
> > On Fri, 12 Mar 2021 18:19:08 +0100
> > Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> >   
> > > On 12.03.21 18:03, Marek Behun wrote:  
> > > > On Fri, 12 Mar 2021 08:34:41 -0800
> > > > Tim Harvey <tharvey at gateworks.com> wrote:
> > > >    
> > > >> On Fri, Mar 12, 2021 at 5:47 AM Marek Behún <marek.behun at nic.cz> wrote:    
> > > >>>
> > > >>> Enable LTO for some boards that were tested by people on U-Boot Mailing
> > > >>> List.
> > > >>>
> > > >>> Signed-off-by: Marek Behún <marek.behun at nic.cz>
> > > >>> Tested-by: Adam Ford <aford173 at gmail.com>
> > > >>> Tested-by: Pali Rohár <pali at kernel.org>
> > > >>> Tested-by: Tim Harvey <tharvey at gateworks.com>
> > > >>> ---
> > > >>>  configs/am3517_evm_defconfig          | 1 +
> > > >>>  configs/da850evm_defconfig            | 1 +
> > > >>>  configs/da850evm_direct_nor_defconfig | 1 +
> > > >>>  configs/da850evm_nand_defconfig       | 1 +
> > > >>>  configs/imx6q_logic_defconfig         | 1 +
> > > >>>  configs/imx8mm_beacon_defconfig       | 1 +
> > > >>>  configs/imx8mm_venice_defconfig       | 1 +
> > > >>>  configs/imx8mn_beacon_2g_defconfig    | 1 +
> > > >>>  configs/imx8mn_beacon_defconfig       | 1 +
> > > >>>  configs/nokia_rx51_defconfig          | 1 +
> > > >>>  configs/omap3_logic_defconfig         | 1 +
> > > >>>  configs/r8a774a1_beacon_defconfig     | 1 +
> > > >>>  configs/r8a774b1_beacon_defconfig     | 1 +
> > > >>>  configs/r8a774e1_beacon_defconfig     | 1 +
> > > >>>  configs/turris_mox_defconfig          | 1 +
> > > >>>  configs/turris_omnia_defconfig        | 1 +
> > > >>>  16 files changed, 16 insertions(+)
> > > >>>
> > > >>> diff --git a/configs/am3517_evm_defconfig b/configs/am3517_evm_defconfig
> > > >>> index bae0e0af35..d61eec94a4 100644
> > > >>> --- a/configs/am3517_evm_defconfig
> > > >>> +++ b/configs/am3517_evm_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  # CONFIG_SPL_USE_ARCH_MEMCPY is not set
> > > >>>  # CONFIG_SPL_USE_ARCH_MEMSET is not set
> > > >>> diff --git a/configs/da850evm_defconfig b/configs/da850evm_defconfig
> > > >>> index 26e76a2929..6ff5e21bc6 100644
> > > >>> --- a/configs/da850evm_defconfig
> > > >>> +++ b/configs/da850evm_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_SYS_THUMB_BUILD=y
> > > >>>  CONFIG_ARCH_DAVINCI=y
> > > >>> diff --git a/configs/da850evm_direct_nor_defconfig b/configs/da850evm_direct_nor_defconfig
> > > >>> index d3860a963d..06c7ce7c47 100644
> > > >>> --- a/configs/da850evm_direct_nor_defconfig
> > > >>> +++ b/configs/da850evm_direct_nor_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_CPU_INIT=y
> > > >>>  CONFIG_ARCH_DAVINCI=y
> > > >>> diff --git a/configs/da850evm_nand_defconfig b/configs/da850evm_nand_defconfig
> > > >>> index 0d0e9a148d..be737564e1 100644
> > > >>> --- a/configs/da850evm_nand_defconfig
> > > >>> +++ b/configs/da850evm_nand_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_SYS_THUMB_BUILD=y
> > > >>>  CONFIG_ARCH_DAVINCI=y
> > > >>> diff --git a/configs/imx6q_logic_defconfig b/configs/imx6q_logic_defconfig
> > > >>> index 36dc24d080..0f8aea6983 100644
> > > >>> --- a/configs/imx6q_logic_defconfig
> > > >>> +++ b/configs/imx6q_logic_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_MX6=y
> > > >>>  CONFIG_SYS_TEXT_BASE=0x17800000
> > > >>> diff --git a/configs/imx8mm_beacon_defconfig b/configs/imx8mm_beacon_defconfig
> > > >>> index 045b19f4f3..e8bb44eea6 100644
> > > >>> --- a/configs/imx8mm_beacon_defconfig
> > > >>> +++ b/configs/imx8mm_beacon_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_IMX8M=y
> > > >>>  CONFIG_SYS_TEXT_BASE=0x40200000
> > > >>> diff --git a/configs/imx8mm_venice_defconfig b/configs/imx8mm_venice_defconfig
> > > >>> index a15c3641f6..dff8f64540 100644
> > > >>> --- a/configs/imx8mm_venice_defconfig
> > > >>> +++ b/configs/imx8mm_venice_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_IMX8M=y
> > > >>>  CONFIG_SYS_TEXT_BASE=0x40200000
> > > >>> diff --git a/configs/imx8mn_beacon_2g_defconfig b/configs/imx8mn_beacon_2g_defconfig
> > > >>> index 58b8e49486..1c8cbc2c89 100644
> > > >>> --- a/configs/imx8mn_beacon_2g_defconfig
> > > >>> +++ b/configs/imx8mn_beacon_2g_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_IMX8M=y
> > > >>>  CONFIG_SYS_TEXT_BASE=0x40200000
> > > >>> diff --git a/configs/imx8mn_beacon_defconfig b/configs/imx8mn_beacon_defconfig
> > > >>> index d6a3385d8d..6457b9409a 100644
> > > >>> --- a/configs/imx8mn_beacon_defconfig
> > > >>> +++ b/configs/imx8mn_beacon_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_IMX8M=y
> > > >>>  CONFIG_SYS_TEXT_BASE=0x40200000
> > > >>> diff --git a/configs/nokia_rx51_defconfig b/configs/nokia_rx51_defconfig
> > > >>> index 312ca3a1a9..85ca627790 100644
> > > >>> --- a/configs/nokia_rx51_defconfig
> > > >>> +++ b/configs/nokia_rx51_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  # CONFIG_SYS_THUMB_BUILD is not set
> > > >>>  CONFIG_ARCH_OMAP2PLUS=y
> > > >>> diff --git a/configs/omap3_logic_defconfig b/configs/omap3_logic_defconfig
> > > >>> index 4e37237b86..cc4b727a2c 100644
> > > >>> --- a/configs/omap3_logic_defconfig
> > > >>> +++ b/configs/omap3_logic_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  # CONFIG_SPL_USE_ARCH_MEMCPY is not set
> > > >>>  # CONFIG_SPL_USE_ARCH_MEMSET is not set
> > > >>> diff --git a/configs/r8a774a1_beacon_defconfig b/configs/r8a774a1_beacon_defconfig
> > > >>> index 2f45edd92e..9dd5d9192e 100644
> > > >>> --- a/configs/r8a774a1_beacon_defconfig
> > > >>> +++ b/configs/r8a774a1_beacon_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_RMOBILE=y
> > > >>>  CONFIG_SYS_TEXT_BASE=0x50000000
> > > >>> diff --git a/configs/r8a774b1_beacon_defconfig b/configs/r8a774b1_beacon_defconfig
> > > >>> index ca514bb1aa..b7d7f23f5a 100644
> > > >>> --- a/configs/r8a774b1_beacon_defconfig
> > > >>> +++ b/configs/r8a774b1_beacon_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_RMOBILE=y
> > > >>>  CONFIG_SYS_TEXT_BASE=0x50000000
> > > >>> diff --git a/configs/r8a774e1_beacon_defconfig b/configs/r8a774e1_beacon_defconfig
> > > >>> index b89729d92a..3e44edf29f 100644
> > > >>> --- a/configs/r8a774e1_beacon_defconfig
> > > >>> +++ b/configs/r8a774e1_beacon_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_RMOBILE=y
> > > >>>  CONFIG_SYS_TEXT_BASE=0x50000000
> > > >>> diff --git a/configs/turris_mox_defconfig b/configs/turris_mox_defconfig
> > > >>> index f938fbb475..2a351d9180 100644
> > > >>> --- a/configs/turris_mox_defconfig
> > > >>> +++ b/configs/turris_mox_defconfig
> > > >>> @@ -1,3 +1,4 @@
> > > >>> +CONFIG_LTO=y
> > > >>>  CONFIG_ARM=y
> > > >>>  CONFIG_ARCH_CPU_INIT=y
> > > >>>  CONFIG_ARCH_MVEBU=y
> > > >>> diff --git a/configs/turris_omnia_defconfig b/configs/turris_omnia_defconfig
> > > >>> index 4b8843d7be..d7a2ec3592 100644
> > > >>> --- a/configs/turris_omnia_defconfig
> > > >>> +++ b/configs/turris_omnia_defconfig
> > > >>> @@ -1,3 +1,4 @@    
> > > >>> +CONFIG_LTO=y>>>  CONFIG_ARM=y    
> > > >>>  CONFIG_ARCH_CPU_INIT=y
> > > >>>  CONFIG_SPL_SYS_THUMB_BUILD=y
> > > >>> --
> > > >>> 2.26.2
> > > >>>    
> > > >>
> > > >> Marek,
> > > >>
> > > >> Perhaps I didn't test the property test before as I did not realize
> > > >> there was a config to be enabled.
> > > >>
> > > >> Enabling CONFIG_LTO breaks linking the SPL (linking uboot is fine):
> > > >>   LTO     spl/u-boot-spl
> > > >> make[2]: *** read jobs pipe: No such file or directory.  Stop.
> > > >> make[2]: *** Waiting for unfinished jobs....
> > > >> lto-wrapper: fatal error: make returned 2 exit status
> > > >> compilation terminated.
> > > >> /usr/src/venice/buildroot/output/host/lib/gcc/aarch64-buildroot-linux-gnu/9.3.0/../../../../aarch64-buildroot-linux-gnu/bin/ld:
> > > >> error: lto-wrapper failed
> > > >> collect2: error: ld returned 1 exit status
> > > >> scripts/Makefile.spl:461: recipe for target 'spl/u-boot-spl' failed
> > > >> make[1]: *** [spl/u-boot-spl] Error 1
> > > >> Makefile:1985: recipe for target 'spl/u-boot-spl' failed
> > > >> make: *** [spl/u-boot-spl] Error 2
> > > >>
> > > >> I'm using your lto branch
> > > >>
> > > >> Best Regards,
> > > >>
> > > >> Tim    
> > > >
> > > > Tim, try compiling with only one job, i.e.
> > > >   make -j1
> > > >    
> > > 
> > > If parallel build fails, we have a bug in the Makefile. It worked fine
> > > without the LTO patches.  
> > 
> > It may be a problem with GNU make's jobserver. Tom mentioned that
> > there is a known race condition or something...  
> 
> I was unclear at the time, sorry.  Yes, it sounds like there's some race
> condition these patches are adding that needs to be addressed.  By the
> nature of race condition they aren't always easy to trigger, but we
> can't just ignore them if CI doesn't trip on it every time.
> 
> > If only there was a simple way to discover inside the Makefile the
> > number of jobs given to the make command via the -j parameter, we could
> > use -flto=$(JOBS).
> > 
> > I found this
> > https://blog.jgc.org/2015/03/gnu-make-insanity-finding-value-of-j.html  
> 
> Well, how is this being done in the Linux kernel?  Or maybe, sigh, this
> isn't a problem with Clang's LTO which is what is in mainline Linux
> kernel atm.  Maybe
> https://lore.kernel.org/patchwork/project/lkml/list/?series=463749&state=*
> will have some clues, all the same.

Tom, I fear that the only stable and sane solution now is to drop
jobserver and just do -flto, i.e. in one thread. This will increase
compilation time, but will work for everyone.

Another option is to do -flto=NCPUs, but that would contradict user's
choice of -j option, if they chose -j1, for example.

What do you think?

Marek

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