[PATCH v3 07/18] pxe: Move pxe_utils files

[Tom Rini]

On Thu, Feb 10, 2022 at 07:56:52AM -0600, Adam Ford wrote:
> On Wed, Feb 9, 2022 at 11:16 AM Simon Glass <sjg at chromium.org> wrote:
> >
> > Hi,
> >
> > On Wed, 9 Feb 2022 at 05:32, Tom Rini <trini at konsulko.com> wrote:
> > >
> > > On Wed, Feb 09, 2022 at 05:40:03AM -0600, Adam Ford wrote:
> > > > On Thu, Oct 14, 2021 at 1:50 PM Simon Glass <sjg at chromium.org> wrote:
> > > > >
> > > > > Move the header file into the main include/ directory so we can use it
> > > > > from the bootmethod code. Move the C file into boot/ since it relates to
> > > > > booting.
> > > > >
> > > > +cc lokeshvutla at ti.com
> > > >
> > > > Simon,
> > > >
> > > > I can't explain why, but with git bisect, it appears this patch breaks
> > > > my omap3_logic board (DM3730) by making it wrongly think there is 4GB
> > > > of RAM, when in reality there is only 256MB.  We have both 256MB and
> > > > 512MB parts, and the automatic memory detection has always 'just
> > > > worked' in the past.
> > > >
> > > > With this patch now, I see:
> > > > U-Boot 2022.01-rc1-00185-g262cfb5b15 (Feb 09 2022 - 05:23:42 -0600)
> > > >
> > > > OMAP3630/3730-GP ES1.2, CPU-OPP2, L3-200MHz, Max CPU Clock 1 GHz
> > > > Model: LogicPD Zoom DM3730 Torpedo + Wireless Development Kit
> > > > DRAM:  4 GiB
> > > > <hang>
> > > >
> > > > With the previous commit, 8018b9af57b5 ("pxe: Tidy up the is_pxe
> > > > global"), it properly detects the RAM and fully boots.
> > > >
> > > > U-Boot 2022.01-rc1-00184-g8018b9af57 (Feb 09 2022 - 05:21:39 -0600)
> > > >
> > > > OMAP3630/3730-GP ES1.2, CPU-OPP2, L3-200MHz, Max CPU Clock 1 GHz
> > > > Model: LogicPD Zoom DM3730 Torpedo + Wireless Development Kit
> > > > DRAM:  256 MiB
> > > > NAND:  512 MiB
> > > > MMC:   OMAP SD/MMC: 0
> > > > Loading Environment from NAND... OK
> > > > OMAP die ID: 619e00029ff800000168300f1502501f
> > > > Net:   eth0: ethernet at 08000000
> > > > Hit any key to stop autoboot:  0
> > > > OMAP Logic #
> > > >
> > > > I have CONFIG_CMD_BOOTM,  CONFIG_CMD_PXE and CONFIG_CMD_SYSBOOT all
> > > > defined, so I am having a hard time understanding why this would
> > > > change behavior or stomp on the the structure that knows the memory
> > > > size.
> > > >
> > > > If I jump ahead to the current 'master' 531c0089457:("Merge branch
> > > > '2022-02-08-TI-platform-updates')  and revert this patch, my board
> > > > boots correctly again, but I am struggling to understand why.
> + Marek Behún
> 
> > > >
> > > > Do you have any suggestions for me to try?
> > >
> > > I would suggest objdump disassemble U-Boot before/after and see what
> > > functions have changed.
> >
> > Keep an eye out for a BSS variable that is used before relocation, perhaps?
> 
> I am still investigating, but disabling LTO appears to fix the issue
> for me.  I'd like to keep LTO, so I'm going to attempt to focus on the
> differences in the affected functions and how this patch makes LTO
> behave differently.
> 
> The disassembly of U-Boot is large, so it's going to take me a bit of
> time to investigate.  If someone has any LTO-related suggestions that
> I could try, I'd be open to try them too.

Wait, the disassembly is large, or the differences between the
disassembly, before/after this change alone, are large?  It's feeling
like just how we remove the LTO flags from
arch/arm/mach-omap2/omap3/board.o something else might also need that,
OR digging more to find out issue LTO is exposing in terms of variables
being in the data and not BSS section and needing initialization or
similar.

-- 
Tom
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