Re: git: 39fdad34e220 - main - stand: impose 510,000 byte limit for /boot/loader and /boot/pxeldr
Date: Thu, 11 Aug 2022 19:07:15 UTC
Am Thu, 11 Aug 2022 20:56:05 +0200
FreeBSD User <freebsd@walstatt-de.de> schrieb:
> Am Thu, 11 Aug 2022 12:46:46 -0600
> Warner Losh <imp@bsdimp.com> schrieb:
>
> > On Thu, Aug 11, 2022 at 12:45 PM FreeBSD User <freebsd@walstatt-de.de>
> > wrote:
> >
> > > Am Thu, 11 Aug 2022 20:42:57 +0200
> > > FreeBSD User <freebsd@walstatt-de.de> schrieb:
> > >
> > > > Am Thu, 11 Aug 2022 12:23:59 -0600
> > > > Warner Losh <imp@bsdimp.com> schrieb:
> > > >
> > > > > On Thu, Aug 11, 2022 at 12:22 PM FreeBSD User <freebsd@walstatt-de.de>
> > > > > wrote:
> > > > >
> > > > > > Am Thu, 11 Aug 2022 03:31:36 GMT
> > > > > > Warner Losh <imp@FreeBSD.org> schrieb:
> > > > > >
> > > > > > > The branch main has been updated by imp:
> > > > > > >
> > > > > > > URL:
> > > > > >
> > > https://cgit.FreeBSD.org/src/commit/?id=39fdad34e220c52a433e78f20c8c39412429014e
> > >
> > > > > > >
> > > > > > > commit 39fdad34e220c52a433e78f20c8c39412429014e
> > > > > > > Author: Warner Losh <imp@FreeBSD.org>
> > > > > > > AuthorDate: 2022-08-11 03:19:01 +0000
> > > > > > > Commit: Warner Losh <imp@FreeBSD.org>
> > > > > > > CommitDate: 2022-08-11 03:29:20 +0000
> > > > > > >
> > > > > > > stand: impose 510,000 byte limit for /boot/loader and
> > > /boot/pxeldr
> > > > > > >
> > > > > > > The BIOS method of booting imposes an absolute limit of 640k
> > > for the
> > > > > > > size of the program being run due to btx. In practice, this
> > > means
> > > > > > that
> > > > > > > programs larger than about 500kiB will fail in odd ways as the
> > > stack
> > > > > > /
> > > > > > > heap will overflow.
> > > > > > >
> > > > > > > Pick 510,000 as the cutoff line semi-arbitrarily. loader_lua
> > > is now
> > > > > > > almost too big and we want to break the build when it crosses
> > > this
> > > > > > > threshold. In my experience, below 500,000 always works,
> > > above
> > > > > > 520,000
> > > > > > > always seems to fail with things getting bad somewhere
> > > between
> > > > > > 512,000
> > > > > > > to 515,000. 510,000 is as close to the line as I think we can
> > > go,
> > > > > > though
> > > > > > > experience may dictate we need to lower this in the future.
> > > > > > >
> > > > > > > This is at-best a stop-breakage until we have a better way to
> > > subset
> > > > > > the
> > > > > > > boot loader for BIOS booting to allow better, more fined-tuned
> > > > > > > /boot/loaders for the many different environments they have to
> > > run
> > > > > > > in. This likely means we'll have a graphical loader than
> > > understands
> > > > > > a
> > > > > > > few filesystmes for installation, and a non-graphical loader
> > > that
> > > > > > > understands the most filesystems possible for everything else
> > > in the
> > > > > > > future. Our build infrastructure needs some work before we can
> > > do
> > > > > > that,
> > > > > > > however.
> > > > > > >
> > > > > > > At this late date, it likely isn't worth the efforts to move
> > > parts of
> > > > > > > the loader into high memory. There's a number of assumptions
> > > about
> > > > > > where
> > > > > > > the stack is, where buffers reside, etc that are fulfilled
> > > when it
> > > > > > lives
> > > > > > > in the first 640k that would need bounce buffers and/or other
> > > counter
> > > > > > > measures if we were to split it up. All BIOS calls are done in
> > > 16-bit
> > > > > > > mode with SEG:OFF addresses, requiring them to be in the first
> > > 640k
> > > > > > of
> > > > > > > RAM. And nearly all machines in the last decade can boot with
> > > UEFI
> > > > > > > (though there's some exceptions, so it isn't worth killing
> > > outright
> > > > > > > yet).
> > > > > > >
> > > > > > > Sponsored by: Netflix
> > > > > > > Reviewed by: kevans
> > > > > > > Differential Revision: https://reviews.freebsd.org/D36129
> > > > > > > ---
> > > > > > > stand/i386/loader/Makefile | 5 +++++
> > > > > > > stand/i386/pxeldr/Makefile | 3 +++
> > > > > > > 2 files changed, 8 insertions(+)
> > > > > > >
> > > > > > > diff --git a/stand/i386/loader/Makefile
> > > b/stand/i386/loader/Makefile
> > > > > > > index 3685281ffd2c..cde1513aac06 100644
> > > > > > > --- a/stand/i386/loader/Makefile
> > > > > > > +++ b/stand/i386/loader/Makefile
> > > > > > > @@ -19,6 +19,8 @@ PROG= ${LOADER}.sym
> > > > > > > INTERNALPROG=
> > > > > > > NEWVERSWHAT?= "bootstrap loader" x86
> > > > > > > VERSION_FILE= ${.CURDIR}/../loader/version
> > > > > > > +LOADERSIZE= 510000 # Largest known safe size
> > > > > > > +
> > > > > > >
> > > > > > > .PATH: ${BOOTSRC}/i386/loader
> > > > > > >
> > > > > > > @@ -79,9 +81,12 @@ CFLAGS+= -I${BOOTSRC}/i386
> > > > > > > 8x16.c: ${SRCTOP}/contrib/terminus/ter-u16b.bdf
> > > > > > > vtfontcvt -f compressed-source -o ${.TARGET} ${.ALLSRC}
> > > > > > >
> > > > > > > +
> > > > > > > ${LOADER}: ${LOADER}.bin ${BTXLDR} ${BTXKERN}
> > > > > > > btxld -v -f elf -e ${LOADER_ADDRESS} -o ${.TARGET} -l
> > > ${BTXLDR} \
> > > > > > > -b ${BTXKERN} ${LOADER}.bin
> > > > > > > + @set -- `${SIZE} ${.TARGET} | tail -1` ;
> > > > > > x=$$((${LOADERSIZE}-$$4)); \
> > > > > > > + echo "$$x bytes available"; test $$x -ge 0
> > > > > > >
> > > > > > > ${LOADER}.bin: ${LOADER}.sym
> > > > > > > ${STRIPBIN} -R .comment -R .note -o ${.TARGET} ${.ALLSRC}
> > > > > > > diff --git a/stand/i386/pxeldr/Makefile
> > > b/stand/i386/pxeldr/Makefile
> > > > > > > index a44dc0de2885..f8bc1eae9a31 100644
> > > > > > > --- a/stand/i386/pxeldr/Makefile
> > > > > > > +++ b/stand/i386/pxeldr/Makefile
> > > > > > > @@ -13,6 +13,7 @@ BOOT= pxeboot
> > > > > > > LDR= pxeldr
> > > > > > > ORG= 0x7c00
> > > > > > > LOADER= loader
> > > > > > > +PXELDRSIZE= 510000 # Largest known safe size
> > > > > > >
> > > > > > > .if defined(BOOT_PXELDR_PROBE_KEYBOARD)
> > > > > > > CFLAGS+=-DPROBE_KEYBOARD
> > > > > > > @@ -41,5 +42,7 @@ CLEANFILES+= ${LOADER}
> > > > > > > ${LOADER}: ${LOADERBIN} ${BTXLDR} ${BTXKERN}
> > > > > > > btxld -v -f elf -e ${LOADER_ADDRESS} -o ${.TARGET} -l
> > > ${BTXLDR} \
> > > > > > > -b ${BTXKERN} ${LOADERBIN}
> > > > > > > + @set -- `${SIZE} ${.TARGET} | tail -1` ;
> > > > > > x=$$((${PXELDRSIZE}-$$4)); \
> > > > > > > + echo "$$x bytes available"; test $$x -ge 0
> > > > > > >
> > > > > > > .include <bsd.prog.mk>
> > > > > > >
> > > > > >
> > > > > > On recent CURRENT (FreeBSD 14.0-CURRENT #10
> > > main-n257258-348164aa9e5d: Wed
> > > > > > Aug 10 22:39:17
> > > > > > CEST 2022 amd64), buildworld fails here on several boxes:
> > > > > >
> > > > > > [...]
> > > > > >
> > > > > > ===> lib/flua/libjail (all)
> > > > > > --- all_subdir_stand ---
> > > > > > --- loader ---
> > > > > > btxld -v -f elf -e 0x200000 -o loader -l
> > > > > > /usr/obj/usr/src/amd64.amd64/stand/i386/btx/btxldr/btxldr -b
> > > > > > /usr/obj/usr/src/amd64.amd64/stand/i386/btx/btx/btx
> > > > > > /usr/obj/usr/src/amd64.amd64/stand/i386/loader_lua/loader_lua.bin
> > > kernel:
> > > > > > ver=1.02 size=690
> > > > > > load=9000 entry=9010 map=16M pgctl=0:84 client: fmt=elf size=8a3f0
> > > > > > text=836bc data=5238
> > > > > > bss=8070 entry=0 output: fmt=elf size=8ae39 text=289 data=8aa80
> > > org=200000
> > > > > > entry=200000
> > > > > > -58585 bytes available 6.64 real
> > > > > > 8.48 user 2.84 sys
> > > > > >
> > > > >
> > > > > I'm sorry, but however you are building /boot/loader, it won't work
> > > when
> > > > > it's that big. What are your settings that increase its size by so
> > > much?
> > > > >
> > > > > Warner
> > > >
> > > > Hello,
> > > > I have a custom kernel with several drivers enabled, others disabled,
> > > but I'm not aware of
> > > > any knowb I triggered by purpose that could change the size. Can you
> > > help me with some hints
> > > > which knobs this might trigger? Since it happens on ALL boxes with
> > > CURRENT and different but
> > > > similar custom kernel settings (mostly driver and disabling debugging et
> > > cetera it must be
> > > > something very trivial that triggers that misbehaviour ... I doubt that
> > > kernel config is the
> > > > cause, but anyway, I'll give you some extra configs I put on one box
> > > that fails:
> > > >
> > > > [... kernel conf ...]
> > > >
> > > > # The defaults are 64K and 128K respectively.
> > > > options DFLTPHYS=(64*1024)
> > > > #options MAXPHYS=(512*1024)
> > > > options MAXPHYS=(1024*1024)
> > > >
> > > > options CC_CDG
> > > > options CC_CHD
> > > > options CC_CUBIC
> > > > options CC_DCTCP
> > > > options CC_HD
> > > > options CC_HTCP
> > > > options CC_VEGAS
> > > > options RATELIMIT # TX rate
> > > >
> > > > options ZFS # ZFS
> > > > options GEOM_NOP # NOP GEOM class
> > > > options GEOM_ELI
> > > >
> > > > options LIBICONV # kernels iconv
> > > > options LIBMCHAIN # mchain library
> > > > options KGSSAPI # Kernel GSS API modulue
> > > >
> > > > options MSDOSFS_ICONV # MSDOS Filesystem
> > > > options CD9660_ICONV # ISO 9660 Filesystem
> > > >
> > > > options FDESCFS #File descriptor filesystem
> > > > options FUSEFS #FUSE support module
> > > > options AUTOFS # automounter filesystem
> > > > options NULLFS
> > > >
> > > > #options P1003_1B_SEMAPHORES # POSIX-style semaphores
> > > > #options P1003_1B_MQUEUE # POSIX message queue
> > > >
> > > > options TCPHPTS # TCP High
> > > Precission timer
> > > > #options TCPPCAP # keeps the last n
> > > packets
> > > > #options MROUTING # Multicast routing
> > > > options IPSEC # Internet Protocol
> > > Security protocol
> > > > #options TCP_SIGNATURE # #include support for
> > > RFC 2385
> > > > options SCTP # Stream Control Transmission
> > > Protocol
> > > >
> > > > #
> > > > options MAC_BSDEXTENDED # ugidfw
> > > > options MAC_PORTACL #
> > > > options MAC_NTPD #
> > > > #
> > > > options CAM_IOSCHED_DYNAMIC # CAM iosched NCQ TRIM
> > > >
> > > >
> > > The src.conf:
> > >
> > > # more /etc/src.conf
> > > #
> > > CPUTYPE?= native
> > > #
> > > CFLAGS+= -O3
> > > # for the kernel
> > > COPTFLAGS+= -O3
> > > #
> > > #CXXFLAGS+= -std=c++20
> > > #
> > > WITH_CLANG_EXTRAS= YES
> > > #WITH_LLVM_BINUTILS= YES
> > > #
> > > #WITH_BSD_GREP= YES
> > > #
> > > WITH_OFED_EXTRA= YES
> > > #WITH_CTF= YES
> > > #
> > > WITH_BEARSSL= YES
> > >
> >
> > I think this is the only thing that will affect things. what happens if you
> > turn this off?
> >
> > Warner
>
> Well, I would have asked whether BEARSSL could trigger something ... I can't change this so
> easily, whenever I switch it on or of, I usually have to recompile world beginning from a
> cleanworld ... this takes approx two hours on my superfast Ivy bridge 4 core crap box ...
I was wrong, something has happend with the build tree in the past months since I fiddled
arounf with BEARSSL knob:
essence is: now the build is complete.
But isn't the BEARSSL knob essential for the secure boot features? I was playing around a
while ago, but do not use anything reasonable out of it ...
>
> >
> > #
> > > WITH_SORT_THREADS= YES
> > > #
> > > WITH_ZONEINFO_LEAPSECONDS_SUPPORT= YES
> > > #
> > > WITH_MALLOC_PRODUCTION= YES
> > > #
> > > WITHOUT_ASSERT_DEBUG= YES
> > > WITHOUT_TESTS= YES
> > > WITHOUT_DEBUG_FILES= YES
> > > #
> > > WITHOUT_CLEAN= YES
> > > #
> > > WITHOUT_REPRODUCIBLE_BUILD= YES
> > > #
> > > INSTALL_NODEBUG= YES
> > > #
> > >
> > >
> > >
> > >
> > > --
> > > O. Hartmann
> > >
>
>
>
--
O. Hartmann