Hi Maciej, Alex,
On 3/12/21 9:04 PM, Maciej W. Rozycki wrote:
> On Fri, 12 Mar 2021, Philippe Mathieu-Daudé wrote:
>
>>> but your two options to
>>> choose from are:
>>>
>>> 1. Build for the soft-float ABI (`-msoft-float') where any FP calculations
>>> are compiled such as to be made by the CPU using integer arithmetic.
>>
>> With the Debian toolchain I get:
>>
>> /usr/include/stdio.h:27:10: fatal error: bits/libc-header-start.h: No
>> such file or directory
>> #include <bits/libc-header-start.h>
>> ^~~~~~~~~~~~~~~~~~~~~~~~~~
>
> You need to have a soft-float multilib available. You can use:
>
> $ gcc -print-multi-lib
>
> to see what multilibs are available. You'd have to have one that includes
> `-msoft-float' and `-mabi=n32' both at a time. If there's no such one,
> then you'll have to build your own cross-compiler (including soft-float
> libc).
For Alex:
I tried Maciej suggestion using:
-- >8 --
diff --git a/tests/docker/dockerfiles/debian10.docker
b/tests/docker/dockerfiles/debian10.docker
index d034acbd256..42933538a49 100644
--- a/tests/docker/dockerfiles/debian10.docker
+++ b/tests/docker/dockerfiles/debian10.docker
@@ -23,6 +23,7 @@ RUN apt update && \
ccache \
clang \
dbus \
+ gcc-multilib \
gdb-multiarch \
gettext \
git \
---
Then used qemu/debian-mipsel-cross.
Maciej, I tried your suggestion as follow:
$ mipsel-linux-gnu-gcc --version
mipsel-linux-gnu-gcc (Debian 8.3.0-2) 8.3.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ mipsel-linux-gnu-gcc -print-multi-lib
.;
n32;@mabi=n32
64;@mabi=64
soft-float is not listed, but:
$ touch a.c
$ mipsel-linux-gnu-gcc -mabi=n32 -march=r5900 -msoft-float -c a.c
$ file a.o
a.o: ELF 32-bit LSB relocatable, MIPS, N32 MIPS-III version 1 (SYSV),
not stripped
$ readelf -h a.o
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: REL (Relocatable file)
Machine: MIPS R3000
Version: 0x1
Entry point address: 0x0
Start of program headers: 0 (bytes into file)
Start of section headers: 456 (bytes into file)
Flags: 0x20920026, pic, cpic, abi2, 5900,
mips3
Size of this header: 52 (bytes)
Size of program headers: 0 (bytes)
Number of program headers: 0
Size of section headers: 40 (bytes)
Number of section headers: 13
Section header string table index: 12
So we can compile, but:
$ mipsel-linux-gnu-gcc -mabi=n32 -march=r5900 -msoft-float -L
/usr/lib/mipsel-linux-gnu tests/tcg/mips/test-r5900-dmult.c
/usr/lib/gcc-cross/mipsel-linux-gnu/8/../../../../mipsel-linux-gnu/bin/ld:
/usr/lib/../lib32/Scrt1.o: relocations in generic ELF (EM: 3)
/usr/lib/gcc-cross/mipsel-linux-gnu/8/../../../../mipsel-linux-gnu/bin/ld:
/usr/lib/../lib32/Scrt1.o: error adding symbols: file in wrong format
collect2: error: ld returned 1 exit status
$ mipsel-linux-gnu-readelf -h /usr/lib/mipsel-linux-gnu/Scrt1.o
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: REL (Relocatable file)
Machine: MIPS R3000
Version: 0x1
Entry point address: 0x0
Start of program headers: 0 (bytes into file)
Start of section headers: 908 (bytes into file)
Flags: 0x70001007, noreorder, pic, cpic,
o32, mips32r2
Size of this header: 52 (bytes)
Size of program headers: 0 (bytes)
Number of program headers: 0
Size of section headers: 40 (bytes)
Number of section headers: 15
Section header string table index: 14
The multilib documentation is scarce :)
Also I wondered if I could abuse the linker a bit, knowing the resulting
binary would be crap due to ABI mismatch, and got:
$ mipsel-linux-gnu-gcc -march=r5900 -msoft-float -o test-r5900-dmult
test-r5900-dmult.o
collect2: fatal error: ld terminated with signal 11 [Segmentation
fault], core dumped
compilation terminated.
/usr/lib/gcc-cross/mipsel-linux-gnu/8/../../../../mipsel-linux-gnu/bin/ld:
test-r5900-dmult.o: ABI is incompatible with that of the selected emulation
/usr/lib/gcc-cross/mipsel-linux-gnu/8/../../../../mipsel-linux-gnu/bin/ld:
failed to merge target specific data of file test-r5900-dmult.o
/usr/lib/gcc-cross/mipsel-linux-gnu/8/../../../../mipsel-linux-gnu/bin/ld:
BFD (GNU Binutils for Debian) 2.31.1 assertion fail
../../bfd/elfxx-mips.c:3566
It seems Debian default packages aren't ready for QEMU needs.
Alex, the other options I'm thinking of are:
- Have you build/upload the gentoo-mipsr5900el-cross container
- Commit the test-r5900-dmult binary to the repository
- Craft a test-r5900-dmult in assembler without libc:
$ mipsel-linux-gnu-gcc -mabi=n32 -march=r5900 -msoft-float -o a a.o
-nostdlib -emain
$ readelf -h a
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: DYN (Shared object file)
Machine: MIPS R3000
Version: 0x1
Entry point address: 0x102f0
Start of program headers: 52 (bytes into file)
Start of section headers: 1508 (bytes into file)
Flags: 0x20920026, pic, cpic, abi2, 5900,
mips3
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 9
Size of section headers: 40 (bytes)
Number of section headers: 17
Section header string table index: 16
- Do not include r5900 test in mainstream QEMU
What do you think?
Phil.
