[PATCH v4 0/4] Make seabios linkable with lld

[Fangrui Song]

Another try after
https://mail.coreboot.org/hyperkitty/list/[e-mail]/thread/KBHQU4O...

The only change is the removal of `Makefile: Change ET_EXEC to ET_REL so that lld can link bios.bin.elf`
since 699a4e5d6919cc8eae5342443025ceb6909dc276
("ldnoexec: Add script to remove ET_EXEC flag from intermediate build objects")
has done the same thing.

For your convenience, the patch series is available on https://github.com/MaskRay/seabios/tree/lld

Re-sending. I posted this 3 days but got bounced.
I have now ensured there is my email address record on 
(previously not) https://mail.coreboot.org/postorius/lists/seabios.seabios.org/
as well as https://mail.coreboot.org/hyperkitty/list/[e-mail]/

Fangrui Song (4):
  romlayout.S: Add missing SHF_ALLOC flag to .fixedaddr.\addr
  Make rom16.o linkable with lld
  romlayout32flag.lds: Use `. +=` instead of `. =`
  test-build.sh: Delete unneeded LD capability test

scripts/layoutrom.py  |  8 +++++++-
 scripts/test-build.sh | 42 +-----------------------------------------
 src/romlayout.S       |  2 +-
 3 files changed, 9 insertions(+), 43 deletions(-)

[PATCH v4 1/4] romlayout.S: Add missing SHF_ALLOC flag to .fixedaddr.\addr

[Fangrui Song]

It does not make sense to reference a SHF_ALLOC section from a
non-SHF_ALLOC section via R_386_PC16. Conceptually, even if a
non-SHF_ALLOC is loaded as part of the memory image, the distance
between it and a SHF_ALLOC section may not be a constant, so the linker
cannot reasonably resolve the relocation.

GNU ld allows it but lld will warn. Add the SHF_ALLOC flag.

Signed-off-by: Fangrui Song 
---
 src/romlayout.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/romlayout.S b/src/romlayout.S
index c4a4635..a854783 100644
--- a/src/romlayout.S
+++ b/src/romlayout.S
@@ -587,7 +587,7 @@ entry_18:

// Specify a location in the fixed part of bios area.
         .macro ORG addr
-        .section .fixedaddr.\addr
+        .section .fixedaddr.\addr,"a"
         .endm

ORG 0xe05b

[PATCH v4 2/4] Make rom16.o linkable with lld

[Fangrui Song]

lld requires output section descriptions to be sorted by address.
Just sort the addresses beforehand.

Signed-off-by: Fangrui Song 
---
 scripts/layoutrom.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/layoutrom.py b/scripts/layoutrom.py
index abebf02..fa270ef 100755
--- a/scripts/layoutrom.py
+++ b/scripts/layoutrom.py
@@ -321,6 +321,7 @@ def outXRefs(sections, useseg=0, exportsyms=[], forcedelta=0):

# Write LD script includes for the given sections
 def outSections(sections, useseg=0):
+    sections = sorted(sections, key=lambda x: x.finalloc)
     out = ""
     for section in sections:
         loc = section.finalloc

[PATCH v4 3/4] romlayout32flag.lds: Use `. +=` instead of `. =`

[Fangrui Song]

This improves the portability of the linker script and allows lld to link rom.o

Dot assignment inside an output section has an inconsistent behavior
which makes lld difficult to implement.
See https://bugs.llvm.org/show_bug.cgi?id=43083

Dropping `. =` turns out to be beneficial to older GNU ld as well
because we can delete an ld check detecting "cannot move location
counter backwards".

Signed-off-by: Fangrui Song 
---
 scripts/layoutrom.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/scripts/layoutrom.py b/scripts/layoutrom.py
index fa270ef..7bc4a57 100755
--- a/scripts/layoutrom.py
+++ b/scripts/layoutrom.py
@@ -336,14 +336,19 @@ def outRelSections(sections, startsym, useseg=0):
                 if section.finalloc is not None]
     sections.sort(key=operator.itemgetter(0))
     out = ""
+    location = "_reloc_init_end"
     for addr, section in sections:
         loc = section.finalloc
         if useseg:
             loc = section.finalsegloc
-        out += ". = ( 0x%x - %s ) ;\n" % (loc, startsym)
+        if location == "_reloc_init_end":
+            out += ". += 0x%x - %s ;\n" % (loc, location)
+        elif location < loc:
+            out += ". += 0x%x ;\n" % (loc-location,)
         if section.name in ('.rodata.str1.1', '.rodata'):
             out += "_rodata%s = . ;\n" % (section.fileid,)
         out += "*%s.*(%s)\n" % (section.fileid, section.name)
+        location = loc + section.size
     return out

# Build linker script output for a list of relocations.

[PATCH v4 4/4] test-build.sh: Delete unneeded LD capability test

[Fangrui Song]

The previous commit changed romlayout32flag.lds to use `. += ` instead
of `. =`.
We no longer need the LD capability test checking
https://sourceware.org/bugzilla/show_bug.cgi?id=12726

Signed-off-by: Fangrui Song 
---
 scripts/test-build.sh | 42 +-----------------------------------------
 1 file changed, 1 insertion(+), 41 deletions(-)

diff --git a/scripts/test-build.sh b/scripts/test-build.sh
index 25cc2f2..8b35d6f 100755
--- a/scripts/test-build.sh
+++ b/scripts/test-build.sh
@@ -4,50 +4,10 @@
 mkdir -p ${OUT}
 TMPFILE1=${OUT}/tmp_testcompile1.c
 TMPFILE1o=${OUT}/tmp_testcompile1.o
-TMPFILE1_ld=${OUT}/tmp_testcompile1.lds
 TMPFILE2=${OUT}/tmp_testcompile2.c
 TMPFILE2o=${OUT}/tmp_testcompile2.o
 TMPFILE3o=${OUT}/tmp_testcompile3.o

-# Test if ld's alignment handling is correct.  This is a known problem
-# with the linker that ships with Ubuntu 11.04.
-cat - > $TMPFILE1 <<EOF
-const char v1[] __attribute__((section(".text.v1"))) = "0123456789";
-const char v2[] __attribute__((section(".text.v2"))) = "0123456789";
-EOF
-cat - > $TMPFILE1_ld <<EOF
-SECTIONS
-{
-     .mysection 0x88f0 : {
-. = 0x10 ;
-*(.text.v1)
-. = 0x20 ;
-*(.text.v2)
-. = 0x30 ;
-     }
-}
-EOF
-$CC -O -g -c $TMPFILE1 -o $TMPFILE1o > /dev/null 2>&1
-if [ $? -ne 0 ]; then
-    echo "Unable to execute the C compiler ($CC)." >&2
-    echo "" >&2
-    echo "Please install a working compiler and retry." >&2
-    echo -1
-    exit 0
-fi
-$LD -T $TMPFILE1_ld $TMPFILE1o -o $TMPFILE2o > /dev/null 2>&1
-if [ $? -ne 0 ]; then
-    echo "The version of LD on this system ($LD) does not properly handle" >&2
-    echo "alignments.  As a result, this project can not be built." >&2
-    echo "" >&2
-    echo "The problem may be the result of this LD bug report:" >&2
-    echo " http://sourceware.org/bugzilla/show_bug.cgi?id=12726" >&2
-    echo "" >&2
-    echo "Please update to a working version of binutils and retry." >&2
-    echo -1
-    exit 0
-fi
-
 # Test for "-fwhole-program".  Older versions of gcc (pre v4.1) don't
 # support the whole-program optimization - detect that.
 $CC -fwhole-program -S -o /dev/null -xc /dev/null > /dev/null 2>&1
@@ -87,4 +47,4 @@ echo 0
 # "ebp" register is clobberred in an "asm" statement.  The code has
 # been modified to not clobber "ebp" - no test is available yet.

-rm -f $TMPFILE1 $TMPFILE1o $TMPFILE1_ld $TMPFILE2 $TMPFILE2o $TMPFILE3o
+rm -f $TMPFILE1 $TMPFILE1o $TMPFILE2 $TMPFILE2o $TMPFILE3o

[Joseph Mingrone]

On Tue, 2022-07-12 at 18:35, Fangrui Song via SeaBIOS  wrote:
> Another try after
> https://mail.coreboot.org/hyperkitty/list/[e-mail]/thread/KBHQU4O...
> The only change is the removal of `Makefile: Change ET_EXEC to ET_REL so that lld can link bios.bin.elf`
> since 699a4e5d6919cc8eae5342443025ceb6909dc276
> ("ldnoexec: Add script to remove ET_EXEC flag from intermediate build objects")
> has done the same thing.
> For your convenience, the patch series is available on https://github.com/MaskRay/seabios/tree/lld
> Re-sending. I posted this 3 days but got bounced.
> I have now ensured there is my email address record on 
> (previously not) https://mail.coreboot.org/postorius/lists/seabios.seabios.org/
> as well as https://mail.coreboot.org/hyperkitty/list/[e-mail]/
> Fangrui Song (4):
>   romlayout.S: Add missing SHF_ALLOC flag to .fixedaddr.\addr
>   Make rom16.o linkable with lld
>   romlayout32flag.lds: Use `. +=` instead of `. =`
>   test-build.sh: Delete unneeded LD capability test
> scripts/layoutrom.py  |  8 +++++++-
>  scripts/test-build.sh | 42 +-----------------------------------------
>  src/romlayout.S       |  2 +-
>  3 files changed, 9 insertions(+), 43 deletions(-)

Hello all,

FreeBSD ports developer here.  Is there anything we can do to help get
this series of patches evaluated?

Thanks,

Joe

[Kevin O'Connor]

On Wed, Nov 30, 2022 at 05:46:26PM -0400, Joseph Mingrone wrote:
> On Tue, 2022-07-12 at 18:35, Fangrui Song via SeaBIOS  wrote:
> > Another try after
> > https://mail.coreboot.org/hyperkitty/list/[e-mail]/thread/KBHQU4O...
>
> Hello all,
>
> FreeBSD ports developer here.  Is there anything we can do to help get
> this series of patches evaluated?

Can you elaborate on the part of the series that you need and why it
is needed?

This changeset has a long history and there is little desire to
revisit it.

https://www.mail-archive.com/[e-mail]/msg12169.html
https://www.mail-archive.com/[e-mail]/msg12285.html
https://www.mail-archive.com/[e-mail]/msg12683.html

-Kevin

[Joseph Mingrone]

On Wed, 2022-12-07 at 13:24, Kevin O'Connor  wrote:
> On Wed, Nov 30, 2022 at 05:46:26PM -0400, Joseph Mingrone wrote:
> > On Tue, 2022-07-12 at 18:35, Fangrui Song via SeaBIOS  wrote:
> > > Another try after
> > > https://mail.coreboot.org/hyperkitty/list/[e-mail]/thread/KBHQU4O...
> > Hello all,
> > FreeBSD ports developer here.  Is there anything we can do to help get
> > this series of patches evaluated?
> Can you elaborate on the part of the series that you need and why it
> is needed?
> This changeset has a long history and there is little desire to
> revisit it.
> https://www.mail-archive.com/[e-mail]/msg12169.html
> https://www.mail-archive.com/[e-mail]/msg12285.html
> https://www.mail-archive.com/[e-mail]/msg12683.html
> -Kevin

Hello,

I don't understand all the constraints and history, but it would be nice
to be able to build SeaBIOS on FreeBSD with our in-tree tools.  The
differences between LLVM objdump and GNU objdump means that swapping in
LLVM objdump is not straightforward.

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=267854

Joe