[PATCH v3 07/18] pxe: Move pxe_utils files
Tom Rini
trini at konsulko.com
Fri Feb 11 17:12:08 CET 2022
On Fri, Feb 11, 2022 at 09:50:32AM -0600, Adam Ford wrote:
> On Thu, Feb 10, 2022 at 8:57 AM Tom Rini <trini at konsulko.com> wrote:
> >
> > 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
>
> I will be the first to admit thatI am not very good with the assembly
> side of things, but this is what I did:
>
> git checkout master
> make CROSS_COMPILE=arm-linux-gnueabihf- -j8
> arm-linux-gnueabihf-objdump -S u-boot > broken.dump
> git revert 262cfb5b15420a1aea465745a821e684b3dfa153
> make CROSS_COMPILE=arm-linux-gnueabihf- -j8
> arm-linux-gnueabihf-objdump -S u-boot > working.dump
>
> diff --side-by-side --suppress-common-lines broken.dump working.dump
> > broken-working.diff
> cat -n broken-working.diff
>
> The broken-working.diff file with common lines suppressed is 236256 lines long.
OK, I just use '-d' and not '-S', which might help a little bit. But
you're probably going to still need to edit the dumps and just globally
change all of the addresses to 'XXXXXXXX' so that you'll end up
hopefully only seeing where functions were optimized differently. But
it might well end up being a bit trickier than that.
> When I disable LTO for just pxe_utils.o and redo the same exercise,
> the diff file with common-lines removed is 266573 lines long.
>
> Maybe I am not using objdump correctly. I am not all that familiar
> with this code either, so I am not sure which variables should be in
> BSS. I did a search in both working and non-working dumps to look for
> keyworks like BSS, but from what I can tell, both have similar
> functions:
>
> gd->mon_len = (ulong)&__bss_end - (ulong)_start;
> /* TODO: use (ulong)&__bss_end - (ulong)&__text_start; ? */
> gd->mon_len = (ulong)&__bss_end - CONFIG_SYS_MONITOR_BASE;
> gd->mon_len = (ulong)&__bss_end - (ulong)_start;
> * reserve memory for U-Boot code, data & bss
> 8011051a <clear_bss>:
> #if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_EARLY_BSS)
> CLEAR_BSS
> #if !defined(CONFIG_SPL_BUILD) || !defined(CONFIG_SPL_EARLY_BSS)
> CLEAR_BSS
> CLEAR_BSS
>
> When I grepped for mon_len, both sets of dumps looked nearly identical:
>
> aford at aford-OptiPlex-7050:~/src/u-boot$ grep mon_len working.dump
> lmb_reserve(lmb, (phys_addr_t)(uintptr_t)_start, gd->mon_len);
> 80112724 <setup_mon_len>:
> static int setup_mon_len(void)
> gd->mon_len = (ulong)&__bss_end - (ulong)_start;
> 80112726: 4903 ldr r1, [pc, #12] ; (80112734 <setup_mon_len+0x10>)
> 80112728: 4b03 ldr r3, [pc, #12] ; (80112738 <setup_mon_len+0x14>)
> gd->mon_len = (ulong)&__bss_end - CONFIG_SYS_MONITOR_BASE;
> gd->mon_len = (ulong)&__bss_end - (ulong)_start;
> gd->ram_top = board_get_usable_ram_top(gd->mon_len);
> gd->relocaddr -= gd->mon_len;
> gd->mon_len >> 10, gd->relocaddr);
> ip = mon_lengths[yleap];
>
>
> aford at aford-OptiPlex-7050:~/src/u-boot$ grep mon_len broken.dump
> lmb_reserve(lmb, (phys_addr_t)(uintptr_t)_start, gd->mon_len);
> 80110398 <setup_mon_len>:
> static int setup_mon_len(void)
> gd->mon_len = (ulong)&__bss_end - (ulong)_start;
> 8011039a: 4903 ldr r1, [pc, #12] ; (801103a8 <setup_mon_len+0x10>)
> 8011039c: 4b03 ldr r3, [pc, #12] ; (801103ac <setup_mon_len+0x14>)
> gd->mon_len = (ulong)&__bss_end - CONFIG_SYS_MONITOR_BASE;
> gd->mon_len = (ulong)&__bss_end - (ulong)_start;
> gd->ram_top = board_get_usable_ram_top(gd->mon_len);
> gd->relocaddr -= gd->mon_len;
> gd->mon_len >> 10, gd->relocaddr);
> ip = mon_lengths[yleap];
> aford at aford-OptiPlex-7050:~/src/u-boot$
>
> Since I think I narrowed it down to the pxe_utils.o file, I thought
> I'd do an objdump of both the working and non-working versions of
> pxe_utils.o and this is where it got interesting.
>
> With LTO building pxe_utils.o, the dump looks empty:
>
> arm-linux-gnueabihf-objdump -S boot/pxe_utils.o > pxe-notworking.dump
> cat pxe-notworking.dump
>
> boot/pxe_utils.o: file format elf32-littlearm
>
> ^-- no actual code dump
> If I take the working version of this same file without LTO enabled
> and do a dump, and it's 2291 lines long and full of functions.
>
> I tried adding some __used to the non-static function names, but that
> didn't appear to make any difference to the objdump of pxe_utils.o
I feel like it can't be pxe_utils.o itself but rather how LTO is
behaving before/after that change and sorting the object files
differently. If modifying the dumps like I suggested above doesn't lead
to more clues, and it doesn't seem to matter what toolchain is used (are
you using the gcc-11 from kernel.org that we use in docker and
buildman?), I'll try and look as well.
--
Tom
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