Porting Fiasco.OC to RISC-V - Questions

[Adam Lackorzynski]

Hi,

On Wed Mar 11, 2015 at 17:53:58 +0000, Hesham ALMatary wrote:
> I'm considering porting Fiasco.OC/L4Re to RISC-V architecture (for
> both my research and GSoC). So, I started reading the documentation
> and building the environment (For Fiasco.OC and RISC-V tools), and
> QEMU (the emulator that I'll use initially) is running Hello World
> example just fine.
> 
> After some reading, I wanted to start adding support for building L4Re
> for RISC-V (is this a good start?), and I came up with some questions.
> 
> There are two variants of RISC-V ABI (32 and 64 bit) should I provide
> both or just 64-bit version?

For starting, just choose one. The other type could be done later.

> What are the minimal packages and/or Fiasco.OC system components that
> need to be implemented to get Hello World working? Please correct me
> if the following L4Re list is not right (contains more than needed, or
> lack others):
> 
> "bootstrap, sigma0, moe, Log, libc, libc_minimal, cxx_util, cxx_io,
> cxx_base, cxx_io_kdebug,l4sys-direct, l4sys"

Good list. To find out the exact list you can just do
"make O=... sigma0 moe bootstrap l4re_kernel hello" and then see in the
build directory what was actually built.

But actually for starting, you just need boostrap because then comes the
kernel that needs to work before anything more needs to be done for the
user level components.

> Some of the packages are architecture dependent which need some code
> from other projects (like uclibc), should I add them all? FYI, newlib
> has support for riscv, but uclibc doesn't,

True that uclibc does not support riscv natively. But there's nearly no
architecture dependent code needed, so this is not really an issue.

> how can I make the build
> system choose specific packages for the target architecture (riscv in
> this case) and maybe neglect building others?

One way is putting 'broken' files in to package's root directory (e.g.
l4/pkg/hello/broken). Then there's the SYSTEMS variable which defines
for which architecture a library/program can be compiled for. Its
default is all architecture, so by not changing the default and just
adding riscv-l4f where you want it could also be a way.



Adam
-- 
Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/