Re: [PATCH] target/riscv/kvm: do not use non-portable strerrorname_np()

[Michael Tokarev]

18.12.2023 20:20, Daniel Henrique Barboza wrote:
> On 12/18/23 13:22, Natanael Copa wrote:
> > strerrorname_np is non-portable and breaks building with musl libc.
> >
> > Use strerror(errno) instead, like we do other places.
> >
> > Cc: qemu-stable@nongnu.org
> > Fixes: commit 082e9e4a58ba (target/riscv/kvm: improve 'init_multiext_cfg' error 
> > msg)
> > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2041
> > Buglink: https://gitlab.alpinelinux.org/alpine/aports/-/issues/15541
> > Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
> > ---
> >   target/riscv/kvm/kvm-cpu.c | 18 ++++++++----------
> >   1 file changed, 8 insertions(+), 10 deletions(-)
> >
> > diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
> > index 45b6cf1cfa..117e33cf90 100644
> > --- a/target/riscv/kvm/kvm-cpu.c
> > +++ b/target/riscv/kvm/kvm-cpu.c
> > @@ -832,9 +832,8 @@ static void kvm_riscv_read_multiext_legacy(RISCVCPU *cpu,
> >                   multi_ext_cfg->supported = false;
> >                   val = false;
> >               } else {
> > -                error_report("Unable to read ISA_EXT KVM register %s, "
> > -                             "error code: %s", multi_ext_cfg->name,
> > -                             strerrorname_np(errno));
> > +                error_report("Unable to read ISA_EXT KVM register %s: %s",
> > +                             multi_ext_cfg->name, strerror(errno));
>
>
> The reason I did this change, as described in 082e9e4a58ba mentioned in the 
> commit
> message, was precisely to avoid things like this:
>
> qemu-system-riscv64: Unable to read ISA_EXT KVM register ssaia, error: no such 
> file or directory

If KVM context puts its own unique meaning for ENOENT, maybe something like

 "unable to read KVM register: %s\n", errno == ENOENT ? "no such register" : 
strerror(errno)

would do it better?

To me, "No such file or directory" already tells everything and does not look
weird, but that's because I've seen this error message for all sorts of contexts
and got used to this. It is definitely understandable.

/mjt