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From: Marek Behun <marek.behun@nic.cz>
To: u-boot@lists.denx.de
Subject: [RFC PATCH u-boot 01/12] build: use thin archives instead of incremental linking
Date: Sat, 6 Mar 2021 22:20:26 +0100	[thread overview]
Message-ID: <20210306222026.439ab7e1@nic.cz> (raw)
In-Reply-To: <20210305133728.GX1310@bill-the-cat>

On Fri, 5 Mar 2021 08:37:28 -0500
Tom Rini <trini@konsulko.com> wrote:

> On Fri, Mar 05, 2021 at 09:34:42PM +0800, Bin Meng wrote:
> > Hi Marek,
> > 
> > On Fri, Mar 5, 2021 at 2:17 AM Marek Behun <marek.behun@nic.cz> wrote:  
> > >
> > > On Thu, 4 Mar 2021 18:57:11 +0800
> > > Bin Meng <bmeng.cn@gmail.com> wrote:
> > >  
> > > > Hi Marek,
> > > >
> > > > On Wed, Mar 3, 2021 at 12:13 PM Marek Beh?n <marek.behun@nic.cz> wrote:  
> > > > >
> > > > > Using thin archives instead of incremental linking
> > > > > - saves disk space
> > > > > - works better with dead code elimination
> > > > > - prepares for potential LTO  
> > > >
> > > > The commit message is a little bit confusing. This commit actually
> > > > does 2 things: don't do incremental linking (using --whole-archive),
> > > > and use thin archive (passing T to ar). I believe they are for
> > > > different purposes, so we cannot say "using thin archives instead of
> > > > incremental linking".  
> > > > > -       -Wl,--start-group $(patsubst $(obj)/%,%,$(u-boot-spl-main)) \
> > > > > -       $(patsubst $(obj)/%,%,$(u-boot-spl-platdata)) -Wl,--end-group \
> > > > > +       -Wl,--whole-archive $(patsubst $(obj)/%,%,$(u-boot-spl-main)) -Wl,--no-whole-archive \
> > > > > +       -Wl,--start-group $(patsubst $(obj)/%,%,$(u-boot-spl-platdata)) -Wl,--end-group \  
> > > >
> > > > u-boot-spl-platdata is still within --start-group, --end-group, is
> > > > this intentional?  
> > >
> > > I confess that I did not really study these options, I have made these
> > > changes according to old LTO patches for Linux. But you are right that
> > > it does not make sense. I have fixed this for the next version of this
> > > patch.
> > >  
> > > > Is P required to make everything work?  
> > >
> > > It is not. Removed in next version.  
> > 
> > I did more investigation on this.
> > 
> > The Linux kernel specially added P to ar, in below commit:
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9a6cfca4f4130444
> > 
> > So it looks like we should keep P here?
> > 
> > But I don't get the point of switching to thin archives. Based on my
> > experiment, LTO does not rely on thin archives. The Linux kernel did
> > not introduce thin archives for LTO.
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a5967db9af51a84f  
> 
> So technically it would just be part of dealing with the backlog of
> kbuild-resync to take it in this series I guess.
> 

It seems the P flag is needed for ar, otherwise final linking may fail,
for example for nokia rx51. Since Linux uses this as well I am just
gonna put it there.

  reply	other threads:[~2021-03-06 21:20 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-03  4:11 [RFC PATCH u-boot 00/12] U-Boot LTO (Sandbox + ARM Nokia RX-51) Marek Behún
2021-03-03  4:12 ` [RFC PATCH u-boot 01/12] build: use thin archives instead of incremental linking Marek Behún
2021-03-04 10:57   ` Bin Meng
2021-03-04 18:17     ` Marek Behun
2021-03-05 13:34       ` Bin Meng
2021-03-05 13:37         ` Tom Rini
2021-03-06 21:20           ` Marek Behun [this message]
2021-03-05 15:39         ` Marek Behun
2021-03-03  4:12 ` [RFC PATCH u-boot 02/12] sandbox: errno: avoid conflict with libc's errno Marek Behún
2021-03-05  3:00   ` Bin Meng
2021-03-05 15:37     ` Marek Behun
2021-03-05 16:39       ` Simon Glass
2021-03-05 16:50         ` Marek Behun
2021-03-05 16:58           ` Simon Glass
2021-03-05 17:24             ` Heinrich Schuchardt
2021-03-05 17:24             ` Marek Behun
2021-03-05 19:42               ` Simon Glass
2021-03-05 17:21       ` Heinrich Schuchardt
2021-03-07  3:14         ` Marek Behun
2021-03-12  4:45   ` Simon Glass
2021-03-03  4:12 ` [RFC PATCH u-boot 03/12] linker_lists: declare entries and lists externally visible Marek Behún
2021-03-04 13:47   ` Marek Behun
2021-03-05  3:04   ` Bin Meng
2021-03-05 15:49     ` Marek Behun
2021-03-03  4:12 ` [RFC PATCH u-boot 04/12] efi_loader: fix warning when linking with LTO Marek Behún
2021-03-05  5:50   ` Bin Meng
2021-03-03  4:12 ` [RFC PATCH u-boot 05/12] binman: declare symbols externally visible Marek Behún
2021-03-04  0:37   ` Tom Rini
2021-03-04  1:53     ` Marek Behun
2021-03-03  4:12 ` [RFC PATCH u-boot 06/12] build: support building with Link Time Optimizations Marek Behún
2021-03-05  6:34   ` Bin Meng
2021-03-03  4:12 ` [RFC PATCH u-boot 07/12] arch: sandbox: make LTO available Marek Behún
2021-03-03  4:12 ` [RFC PATCH u-boot 08/12] sandbox: build with LTO Marek Behún
2021-03-03  4:12 ` [RFC PATCH u-boot 09/12] ARM: make gd a function for LTO Marek Behún
2021-03-03  4:12 ` [RFC PATCH u-boot 10/12] string: make memcpy() visible to fix LTO linking errors Marek Behún
2021-03-03  4:12 ` [RFC PATCH u-boot 11/12] arch: ARM: make LTO available Marek Behún
2021-03-03  4:12 ` [RFC PATCH u-boot 12/12] Nokia RX-51: build with LTO Marek Behún
2021-03-03 16:11 ` [RFC PATCH u-boot 00/12] U-Boot LTO (Sandbox + ARM Nokia RX-51) Tom Rini
2021-03-03 16:41   ` Marek Behun
2021-03-03 16:47     ` Tom Rini
2021-03-03 21:36     ` Tom Rini
2021-03-04  0:40       ` Adam Ford
2021-03-04  7:07         ` [PATCH] arm: fix LTO build for some thumb-interwork cases Marek Behún
2021-03-04 10:43       ` [RFC PATCH u-boot 00/12] U-Boot LTO (Sandbox + ARM Nokia RX-51) Marek Behun
2021-03-04 13:46         ` Adam Ford
2021-03-04 13:50           ` Marek Behun
2021-03-04 13:59             ` Adam Ford
2021-03-04 14:58           ` Tom Rini
2021-03-04 15:07             ` Adam Ford
2021-03-04 15:37               ` Marek Behun
2021-03-04 16:18                 ` Tom Rini
2021-03-04 15:59               ` Marek Behun
2021-03-04 22:18                 ` Adam Ford
2021-03-04 22:33                   ` Marek Behun
2021-03-05 11:25                     ` Adam Ford
2021-03-05 12:31                       ` Stefan Roese
2021-03-05 17:10                         ` Adam Ford
2021-03-06  3:03                           ` Adam Ford
2021-03-06 11:12                             ` Adam Ford
2021-03-06 17:37                               ` Marek Behun
2021-03-06 20:08                                 ` Tom Rini
2021-03-06 20:41                                   ` Pali Rohár
2021-03-06 20:54                                     ` Marek Behun
2021-03-06 21:00                                       ` Pali Rohár
2021-03-06 21:19                                         ` Marek Behun
2021-03-06 21:38                                           ` Pali Rohár
2021-03-06 21:49                                             ` Marek Behun
2021-03-07  3:45                                               ` Adam Ford
2021-03-07  4:06                                                 ` Marek Behun
2021-05-09 14:14                                                   ` Adam Ford
2021-05-09 18:44                                                     ` Marek Behun
2021-05-10 16:28                                                       ` Simon Glass
2021-05-13  9:22                                                         ` Pali Rohár
2021-03-04 16:17               ` Tom Rini
2021-03-04 16:35                 ` Pali Rohár

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