Re: [Qemu-devel] [PATCH v10 3/3] linux-user: Add support for statx() syscall

[Aleksandar Markovic <aleksandar.m.mail@gmail.com>]

On Wednesday, June 19, 2019, Jim Wilson <jimw@sifive.com> wrote:

> On 6/7/19 3:35 AM, Aleksandar Markovic wrote:
>
>> Implement support for translation of system call statx().
>>
>
> I also need these patches for 32-bit RISC-V linux user mode support.
>
> glibc ld.so calls statx if fstatat is not supported.  Apparently new linux
> architecture ports aren't allowed to define __ARCH_WANT_NEW_STAT which
> enables fstatat because this is already obsolete.  64-bit RISC-V linux does
> have fstatat, but apparently this was a mistake which we can't fix now
> because the ABI is already frozen.  The 32-bit RISC-V ABI is not frozen
> yet, so it won't have fstatat.  Anyways, without statx, ld.so doesn't work,
> which makes user mode qemu pretty useless, so we do need this emulated in
> qemu to make the 32-bit RISC-V linux user mode support work properly.
>
>
Jim, Aleksandar Rikalo, the author of the patch was about to send Laurent
explanation why this aproach is needed in its current organization, on a
very similar line of reasoning as yours.

I am waiting on him to send a new version of the series. Meanwhile you can
send strace patch to the list, and I can even incude it in my series after
and together with Aleksandar's patch, if you don't object.

Yours,

Aleksandar M.

I started with the August 2018 version of the patch a few weeks ago, and
> just noticed that it has been resubmitted.  I had to modify the patch
> slightly to apply to current sources, and had to fix one bug to make it
> work.  The line
> +                if (ret != TARGET_ENOSYS) {
> needs to instead be
> +                if (ret != -TARGET_ENOSYS) {
> I see that Laurent has already pointed that out.
>
> Incidentally, I also have strace patches for statx that work on top of
> this patch, since I didn't see that in the nanomips patch set I started
> with.  That helped me debug the 32-bit RISC-V user mode support.
>
> I've tested this on Ubuntu 16.04 (no host statx) and Ubuntu 19.10 (with
> host statx) and it worked well for me running the gcc testsuite for a
> riscv32-linux target.  I haven't tried testing the latest version of the
> patch yet.  I can do that if this is helpful.
>
> Jim
>
>