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From: Nathan Chancellor <nathan@kernel.org>
To: Palmer Dabbelt <palmer@dabbelt.com>
Cc: twd2.me@gmail.com, linux-riscv@lists.infradead.org,
	ndesaulniers@google.com, llvm@lists.linux.dev
Subject: Re: [PATCH v2] RISC-V: build: Allow LTO to be selected
Date: Fri, 28 Oct 2022 15:57:33 -0700	[thread overview]
Message-ID: <Y1xeXUhnONoB0S6P@dev-arch.thelio-3990X> (raw)
In-Reply-To: <mhng-e9b5bd39-0929-487c-a761-6a3ff508d969@palmer-ri-x1c9>

On Tue, Oct 04, 2022 at 06:57:10PM -0700, Palmer Dabbelt wrote:
> > Allow LTO to be selected for RISC-V, only when LLD >= 14, since there is an
> > issue [1] in prior LLD versions that prevents LLD to generate proper
> > machine code for RISC-V when writing `nop`s.
> > 
> > I have tested enabling LTO for `defconfig`. The LLD took ~2m21s and ~3GiB
> > on our Intel Xeon Gold 6140 server and produced an 18MiB Image. The image
> > can boot to shell using an archriscv rootfs on QEMU.
> > 
> > I have also tested it for `allyesconfig` without COMPILE_TEST, FTRACE,
> > KASAN, and GCOV. The LLD took ~7h03m and ~335GiB on the server,
> > successfully producing a 1.7GiB Image. Unfortunately, we cannot boot this
> > image because the `create_kernel_page_table()` -> `alloc_pmd_early()` ->
> > `BUG_ON()` logic limits the image to be < 1GiB. Maybe we can fix it in a
> > separate patch further.
> > 
> > [1] https://github.com/llvm/llvm-project/issues/50505, resolved by LLVM
> >     commit e63455d5e0e5 ("[MC] Use local MCSubtargetInfo in writeNops")
> > 
> > Tested-by: Wende Tan <twd2.me@gmail.com>
> > Signed-off-by: Wende Tan <twd2.me@gmail.com>
> 
> Sorry for missing this, the v2 never made it to my inbox.  Not sure exactly
> what happened, but an off-list ping made it through.  I've put this on
> for-next, I don't have any way to test it because I don't have clang setup
> yet.
> 

Did this get dropped by accident? I do not see it in your tree.

Cheers,
Nathan

WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <nathan@kernel.org>
To: Palmer Dabbelt <palmer@dabbelt.com>
Cc: twd2.me@gmail.com, linux-riscv@lists.infradead.org,
	ndesaulniers@google.com, llvm@lists.linux.dev
Subject: Re: [PATCH v2] RISC-V: build: Allow LTO to be selected
Date: Fri, 28 Oct 2022 15:57:33 -0700	[thread overview]
Message-ID: <Y1xeXUhnONoB0S6P@dev-arch.thelio-3990X> (raw)
In-Reply-To: <mhng-e9b5bd39-0929-487c-a761-6a3ff508d969@palmer-ri-x1c9>

On Tue, Oct 04, 2022 at 06:57:10PM -0700, Palmer Dabbelt wrote:
> > Allow LTO to be selected for RISC-V, only when LLD >= 14, since there is an
> > issue [1] in prior LLD versions that prevents LLD to generate proper
> > machine code for RISC-V when writing `nop`s.
> > 
> > I have tested enabling LTO for `defconfig`. The LLD took ~2m21s and ~3GiB
> > on our Intel Xeon Gold 6140 server and produced an 18MiB Image. The image
> > can boot to shell using an archriscv rootfs on QEMU.
> > 
> > I have also tested it for `allyesconfig` without COMPILE_TEST, FTRACE,
> > KASAN, and GCOV. The LLD took ~7h03m and ~335GiB on the server,
> > successfully producing a 1.7GiB Image. Unfortunately, we cannot boot this
> > image because the `create_kernel_page_table()` -> `alloc_pmd_early()` ->
> > `BUG_ON()` logic limits the image to be < 1GiB. Maybe we can fix it in a
> > separate patch further.
> > 
> > [1] https://github.com/llvm/llvm-project/issues/50505, resolved by LLVM
> >     commit e63455d5e0e5 ("[MC] Use local MCSubtargetInfo in writeNops")
> > 
> > Tested-by: Wende Tan <twd2.me@gmail.com>
> > Signed-off-by: Wende Tan <twd2.me@gmail.com>
> 
> Sorry for missing this, the v2 never made it to my inbox.  Not sure exactly
> what happened, but an off-list ping made it through.  I've put this on
> for-next, I don't have any way to test it because I don't have clang setup
> yet.
> 

Did this get dropped by accident? I do not see it in your tree.

Cheers,
Nathan

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  parent reply	other threads:[~2022-10-28 22:57 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-12 20:55 [PATCH v2] RISC-V: build: Allow LTO to be selected Wende Tan
2022-05-12 20:55 ` Wende Tan
2022-05-12 21:34 ` Nick Desaulniers
2022-05-12 21:34   ` Nick Desaulniers
2022-05-13 18:28   ` twd2
2022-05-13 18:28     ` twd2
2022-05-13 18:58     ` Fāng-ruì Sòng
2022-05-13 18:58       ` Fāng-ruì Sòng
2022-05-13 19:30     ` Nick Desaulniers
2022-05-13 19:30       ` Nick Desaulniers
2022-05-13 19:31       ` Fāng-ruì Sòng
2022-05-13 19:31         ` Fāng-ruì Sòng
2022-07-01  4:42         ` twd2
2022-07-01  4:42           ` twd2
2022-10-05  1:57 ` Palmer Dabbelt
2022-10-05  1:57   ` Palmer Dabbelt
2022-10-05  2:19   ` Wende Tan
2022-10-05  2:19     ` Wende Tan
2022-10-28 22:57   ` Nathan Chancellor [this message]
2022-10-28 22:57     ` Nathan Chancellor

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