Re: [Qemu-devel] [PATCH 0/2] linux-user: Drop direct use of openat etc syscalls

[Claudio Fontana <claudio.fontana@huawei.com>]

On 02.06.2013 00:35, Peter Maydell wrote:
> The linux-user syscall emulation layer currently supports the openat
> family of syscalls via two mechanisms: simply calling the corresponding
> libc functions, and making direct syscalls. Since glibc has supported
> these functions since at least glibc 2.5, there's no real need to
> retain the (essentially untested) direct syscall fallback code, so
> this patchset simply deletes it.
> 
> This allows us to remove some ifdeffery that was attempting to disable
> provision of some of the syscalls if the host didn't seem to support
> them, which in some cases was actually wrong. For example where there
> are several flavours of the syscall, we only need one of them, not
> necessarily the exact one the guest has, as with the fstatat* calls.
> And if the guest needs the futimesat() syscall we can provide it
> via glibc, even if that syscall is deprecated or not provided in the
> host (because the host implements utimensat instead). AArch64 in
> particular hits the last of these, which resulted in a compile
> failure due to an unused function, because the syscall implementation's
> ifdef was inconsistent with the ifdef used to define the sys_futimesat()
> function.
> 
> Basically, removing the ugly direct syscall access seemed nicer
> than trying to fix up and render consistent the broken ifdefs :-)
> 
> [RHEL5 has glibc2.5 and provides these functions. RHEL4 did not
> but we don't build on RHEL4 anyhow because its glib is too old.
> uClibc provides these functions.]
> 
> Peter Maydell (2):
>   linux-user: Drop direct use of openat etc syscalls
>   configure: Drop CONFIG_ATFILE test
> 
>  configure            |   26 ------
>  linux-user/syscall.c |  218 ++++++--------------------------------------------
>  2 files changed, 24 insertions(+), 220 deletions(-)
> 

Tested on aarch64 with Foundation v8.

Tested-by: Claudio Fontana <claudio.fontana@huawei.com>