Ping.
I was hoping to get this merged in 1.1.20, which didn't happen despite
it getting delayed for a long time. Is there a chance of it happening
soon for 1.1.21?
Yes. I can bump the priority for this.
There hopefully should not be that much more to do on the port to
get it in shape for upstream. Sorry there have been a lot of things
going on so this has fallen through the cracks.
There is still the ELF TLS bug, which shouldn’t be hard to fix, but
we could always mark the port experimental. If it’s in tree; then
more folk may be interested in fixing bugs. The code also needs some
review.
I don't want to merge something with known bugs like this, but I'm
happy to participate in fixing it if I know what the issue is and have
a candidate submission that supposedly works modulo the bug to be
fixed. My understanding is that gcc and qemu stuff is upstream now so
it should be simple to me to build and test. Is this correct?
Okay. We’ll fix the bugs. Yes, there are now several ways to get RISC-V Linux booting in QEMU.
There are riscv cross tools and riscv qemu binaries in Debian Sid. I think it is possible to debootstrap riscv64. Indeed the Debian RISC-V builders are running QEMU.
I also have a bootstrap script for a musl riscv gcc 8.1 compiler here:
You can build the gcc toolchain for comparison:
There are links to several Linux images (Fedora, Debian) and build instructions for Linux kernel and bbl on the RISC-V QEMU wiki:
Alternatively you can clone SiFive’s freedom-u-sdk and type “make qemu” to get a riscv64 buildroot image booting up in QEMU. This same root image and kernel runs on the HiFive Unleashed Board:
Also, Fabrice Belliard has a buildroot port that has recipes for both riscv32 and riscv64:
Normally the kernel is packaged as a payload inside of “bbl”, the Berkeley Boot Loader. However, we now support separate kernel and firmware using the latest bbl, the RISC-V QEMU and “virt” machine in QEMU from the riscv-qemu repository (this feature is not upstream yet) and linux 4.19-rc5 kernel. This is mostly useful if you are recompiling the kernel. We have the -bios, -kernel, -initrd and -append options working:
e.g.
$ qemu-system-riscv64 -nographic -machine virt -bios bbl -kernel vmlinux -initrd initramfs.gz -append rdinit=/bin/busybox
The wiki link above and the freedom-u-sdk have docs and Makefile recipes for attaching VirtIO drives and networking devices.
We moved the port to riscv-musl in the RISC-V GitHub organisation
[1]. We need to rebase and squash the tree and write a commit
message containing the contributors list.
The RISC-V rv32 port isn’t in glibc yet and it may be subject to
change. I need to get a riscv32 Linux kernel running in QEMU so we
can do testing against glibc... I’ll have to chat to Palmer about
riscv32, see if there are any ABI issues we need to be aware of. We
can spend some time this week...
Great!
No worries. It’ll be nice to get the port upstream...
Cheers,
Michael