Please Please put back Sys/io.h emulation for armhf and possibly aarch64

Florian Weimer fweimer@redhat.com
Wed Jun 16 11:34:59 GMT 2021


* Luís Palma Nunes Mendes via Libc-alpha:

> The commit that removed the support, according to Carlos O'Donell was
> this one: The rationale is given in the commit:
>
> commit 6b33f373c7b9199e00ba5fbafd94ac9bfb4337b1
> Author: Florian Weimer
> Date:   Wed May 29 16:53:09 2019 +0200
>
>     arm: Remove ioperm/iopl/inb/inw/inl/outb/outw/outl support
>
>     Linux only supports the required ISA sysctls on StrongARM devices,
>     which are armv4 and no longer tested during glibc development
>     and probably bit-rotted by this point.  (No reported test results,
>     and the last discussion of armv4 support was in the glibc 2.19
>     release notes.)
>
> Except that I was using it with armv7 for PCIe, with the kernel
> configuration:
>
> -> General setup->Configure standard Kernel features (expert
> users)->Sysctl syscall support->Enable

The string “Sysctl syscall support” was removed from the upstream kernel
with this commit:

commit 61a47c1ad3a4dc6882f01ebdc88138ac62d0df03
Author: Eric W. Biederman <ebiederm@xmission.com>
Date:   Tue Oct 1 13:01:19 2019 -0500

    sysctl: Remove the sysctl system call
    
    This system call has been deprecated almost since it was introduced, and
    in a survey of the linux distributions I can no longer find any of them
    that enable CONFIG_SYSCTL_SYSCALL.  The only indication that I can find
    that anyone might care is that a few of the defconfigs in the kernel
    enable CONFIG_SYSCTL_SYSCALL.  However this appears in only 31 of 414
    defconfigs in the kernel, so I suspect this symbols presence is simply
    because it is harmless to include rather than because it is necessary.
    
    As there appear to be no users of the sysctl system call, remove the
    code.  As this removes one of the few uses of the internal kernel mount
    of proc I hope this allows for even more simplifications of the proc
    filesystem.

Which I think went into Linux 5.5.

So we can't support it in glibc now even if we wanted to.

We are not going to bring back this emulation.  Of course, you can take
the old implementation and copy it into your application if that's what
you want.

Thanks,
Florian



More information about the Libc-alpha mailing list