Re: git: 8a62a2a5659d - main - zfs: merge openzfs/zfs@f8e5af53e

On Sat, Mar 21, 2026 at 09:18:20AM -0600, Warner Losh wrote:
> On Sat, Mar 21, 2026, 9:08 AM Shawn Webb <shawn.webb@hardenedbsd.org> wrote:
> 
> > On Sat, Mar 21, 2026 at 09:04:17AM +0100, A FreeBSD User wrote:
> > > Am Tage des Herren Fri, 20 Mar 2026 23:27:20 -0400
> > > Charlie Li <vishwin@freebsd.org> schrieb:
> > >
> > > > Shawn Webb wrote:
> > > > > On Tue, Mar 17, 2026 at 04:52:16PM +0000, Shawn Webb wrote:
> > > > >> On Tue, Mar 17, 2026 at 10:44:59AM -0600, Warner Losh wrote:
> > > > >>> On Tue, Mar 17, 2026 at 10:36 AM Shawn Webb <
> > shawn.webb@hardenedbsd.org>
> > > > >>> wrote:
> > > > >>>
> > > > >>>> Hey Martin,
> > > > >>>>
> > > > >>>> On Sat, Mar 14, 2026 at 01:26:23PM +0000, Martin Matuska wrote:
> > > > >>>>> The branch main has been updated by mm:
> > > > >>>>>
> > > > >>>>> URL:
> > > > >>>>
> > https://cgit.FreeBSD.org/src/commit/?id=8a62a2a5659d1839d8799b4274c04469d7f17c78
> >
> > > > >>>>>
> > > > >>>>> commit 8a62a2a5659d1839d8799b4274c04469d7f17c78
> > > > >>>>> Merge: f91464171d61 f8e5af53e92f
> > > > >>>>> Author:     Martin Matuska <mm@FreeBSD.org>
> > > > >>>>> AuthorDate: 2026-03-14 12:14:56 +0000
> > > > >>>>> Commit:     Martin Matuska <mm@FreeBSD.org>
> > > > >>>>> CommitDate: 2026-03-14 12:14:56 +0000
> > > > >>>>>
> > > > >>>>> [snip for brevity]
> > > > >>>>>
> > > > >>>>>      Obtained from:  OpenZFS
> > > > >>>>>      OpenZFS commit: f8e5af53e92fa7c03393fbd4922cb9c1d0c15920
> > > > >>>>
> > > > >>>> This commit seems to cause issues when building boot loader
> > related
> > > > >>>> code:
> > > > >>>>
> > > > >>>> ==== BEGIN LOG ====
> > > > >>>> 114232 bytes available
> > > > >>>> btxld -v -f aout -e 0x200000 -o loader_simp -l
> > > > >>>> /usr/obj/usr/src/amd64.amd64/stand/i386/btx/btxldr/btxldr  -b
> > > > >>>> /usr/obj/usr/src/amd64.amd64/stand/i386/btx/btx/btx
> > loader_simp.bin
> > > > >>>> kernel: ver=1.02 size=690 load=9000 entry=9010 map=16M pgctl=0:58
> > > > >>>> client: fmt=elf size=5e2e8 text=57930 data=514c bss=7470 entry=0
> > > > >>>> output: fmt=aout size=61000 text=1000 data=5f000 org=200000
> > entry=200000
> > > > >>>> ===> stand/i386/pxeldr (all)
> > > > >>>> -560 bytes available
> > > > >>>> *** Error code 1
> > > > >>>>
> > > > >>>
> > > > >>> What all do you have enabled? The defaults aren't even close to
> > running out
> > > > >>> of space (though I've not looked at this).
> > > > >>
> > > > >> Hey Warner,
> > > > >>
> > > > >> Thanks for reaching out! I've uploaded `make showconfig` here:
> > > > >> https://hardenedbsd.org/~shawn/2026-03-17_srcconf-r01.txt
> > > > >>
> > > > >> The following options are specific to HardenedBSD (in no particular
> > > > >> order):
> > > > >>
> > > > >> 1. MK_HBSD_UPDATE
> > > > >> 2. MK_HBSDCONTROL
> > > > >> 3. MK_PIE
> > > > >> 4. MK_RELRO
> > > > >> 5. MK_SHLIBRANDOM
> > > > >> 6. MK_ZERO_REGS
> > > > >> 7. MK_SPECTREV1_FIX
> > > > >> 8. MK_SAFESTACK
> > > > >> 9. MK_RETPOLINE
> > > > >> 10. MK_LTOLIB
> > > > >> 11. MK_CFI
> > > > >
> > > > > MK_RETPOLINE was the culprit. Something about this ZFS commit causes
> > > > > LLVM to emit more retpoline entries than before--too many for a
> > little
> > > > > bootloader. That might be something to investigate later, but only to
> > > > > satisfy a curious mind, not to actuall fix anything (since nothing's
> > > > > actually broken.)
> > > > >
> > > > > Since it doesn't really make sense to apply speculative execution
> > > > > mitigations to a bootloader, I disabled retpoline for a components
> > > > > in stand/.
> > > > >
> > > > > Good to go.
> > > > >
> > > > Also just got bit by this, albeit during the lua loader, since I have
> > > > WITH_RETPOLINE in my src.conf.
> > > >
> > >
> > > Hello,
> > >
> > > I do not have WITH_RETPOLINE in my /etc/src.conf, but since I got this
> > mysterious error about
> > > not enough bytes left, I use WITHOUT_LOADER_PXEBOOT= YES (due to issues
> > with WITH_BEARSSL=YES
> > > also used).
> > > Despite not using any WITH_RETPOLINE I also catch the error ...
> >
> > Something about this ZFS commit causes the boot laoder to be too big.
> > I guess the first sign of trouble was with retpolines, but there seem
> > to now be additional signs.
> >
> > What's the process for filing a bug report against OpenzFS for
> > something like this? (Not asking you directly, just a general question
> > for the thread.)
> >
> 
> That's a good question. We are rapidly aporoaching the day we will have to
> freeze the set of zfs feature that we can boot with the BIOS path. There's
> only so much space.
> 
> Right now,  there's little to no bootloader testing, let alone analysis
> done and that will need to change.

Another question might also be: is it worth the time and effort? Are
people really using a ZFS-enabled traditional MBR BIOS bootloader on
FreeBSD 16-CURRENT (or eventual 16.0-RELEASE)? From my rather naive
(and ignorant, since I don't know FreeBSD's userbase well), it seems
like folks use either loader.efi or u-boot (or both!)

Not a question I can answer, of course, because everyone likely has a
different take on what "worth the time and effort" means to them. :-)

Thanks,

-- 
Shawn Webb
Cofounder / Security Engineer
HardenedBSD

Signal Username:  shawn_webb.74
Tor-ified Signal: +1 303-901-1600 / shawn_webb_opsec.50
https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc