On 11/24/25 01:18, Philippe Mathieu-Daudé wrote:
On 1/9/25 09:47, Geert Uytterhoeven wrote:
On Sun, 24 Aug 2025 at 20:40, Rob Landley <[email protected]> wrote:
Anyway, this works fine on little endian, but the qemu-system-sh4eb
build has something hinky in the ethernet, I haven't tackled it myself
because I don't know whether the device emulation or the driver is
what's missing an endian swap. (I don't want to fix it the "wrong way",
That is using sh_eth, right?
Last time I tried booting a big-endian ARM kernel on R-Car M2-W,
the Linux kernel booted fine, except for Ethernet. So sh_eth is
definitely
not big-endian clean.
qemu-system-sh4{eb} only emulates the R2D+ board, which AFAIK
provides ethernet via a RTL8139 over PCI. While old, RTL8139
is very tested and expected to have endianness well handled.
Expected, sure. In reality? Compare the sh4 vs sh4eb tarballs in
https://landley.net/bin/mkroot/0.8.13/ (in each case extract and
./run-qemu.sh should get you a shell prompt).
The sh4 one has working ethernet, the sh4eb one always reports link down
and it doesn't seem to probe the mac address right. Built from almost
the same configs, the only difference is:
https://github.com/landley/toybox/blob/0.8.13/mkroot/mkroot.sh#L297
Line 305 adds:
[ "$CROSS" == sh4eb ] && KCONF+=,CPU_BIG_ENDIAN
When I tried to track it down, I didn't know if the kernel or qemu was
what had it backwards, so it went back on the todo heap and composted...
[*] I didn't have a big-endian userspace.
That script builds one, the resulting binary tarball is at
https://landley.net/bin/mkroot/0.8.13/sh2eb.tgz and the toolchain I used
is at
https://landley.net/bin/toolchains/25-03-2024/sh4eb-linux-musl-cross.tar.xz
which was built with https://landley.net/toybox/faq.html#cross2
There might also be something wrong with -hda block device support, I'd
have to check my notes. But I can work around lack of -hda with
nbd-server, kinda hard to do it the other way...
Rob
