Re: Emulating missing linux syscalls

[christos%astron.com@localhost (Christos Zoulas)]

In article <YlV0WgcFGhH/vSIP%bec.de@localhost>, Joerg Sonnenberger  <joerg%bec.de@localhost> wrote:
>Am Tue, Apr 12, 2022 at 12:29:21PM -0000 schrieb Christos Zoulas:
>> In article
><CALigkZQpW8-wAty57d=hpsx6eo_RmacQ=pkej+FezNS_r6Mq=w%mail.gmail.com@localhost>,
>> Piyush Sachdeva  <piyushsachdeva245%gmail.com@localhost> wrote:
>> >-=-=-=-=-=-
>> >
>> >Dear Stephen Borrill,
>> >My name is Piyush, and I was looking into the
>> >'Emulating missing Linux syscalls' project hoping to contribute
>> >to this year's GSoC.
>> >
>> >I wanted to be sure of a few basic things before I go ahead:
>> >- linux binaries are found in- src/sys/compat/linux
>> >- particular implementation in - src/sys/compat/linux/common
>> >- a few architecture-specific implementations in-
>> >  src/sys/compat/linux/arch/<arch_name>.
>> >- The src/sys/compat/linux/arch/<arch_name>/linux_syscalls.c file
>> >   lists of system calls, and states if a particular syscall is present or
>> >not.
>> >
>> >I was planning to work on the 'sendfile()' syscall, which I believe
>> >is unimplemented for amd64 and a few other architectures as well.
>> >
>> >Considering the above points, I was hoping you could point me in
>> >the right direction for this project. Hope to hear from you soon.
>> 
>> I would look into porting the FreeBSD implementation of sendfile to NetBSD.
>
>sendfile(2) for Linux compat can be emulated in the kernel without
>backing. That said, a real splice(2) or even splicev(2) would be really
>nice to have. But that's a different project and arguable, a potentially
>more generally useful one, too.


Yes, splice is more general (as opposed to send a file to a socket), but I
think splice has limitations too (one of the fds needs to be a pipe).
Is that true only for linux?

christos