From: Florian Weimer <fweimer@redhat.com>
To: Alexander Monakov <amonakov@ispras.ru>
Cc: Matheus Afonso Martins Moreira via Gcc <gcc@gcc.gnu.org>,
Matheus Afonso Martins Moreira <matheus.a.m.moreira@gmail.com>
Subject: Re: [RFC] Linux system call builtins
Date: Mon, 08 Apr 2024 13:50:43 +0200 [thread overview]
Message-ID: <87h6gcvzsc.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <5a5b1c2c-6feb-3bf5-cf08-aa93a1b181b8@ispras.ru> (Alexander Monakov's message of "Mon, 8 Apr 2024 14:44:41 +0300 (MSK)")
* Alexander Monakov:
> On Mon, 8 Apr 2024, Florian Weimer via Gcc wrote:
>
>> * Matheus Afonso Martins Moreira via Gcc:
>>
>> > + It's stable
>> >
>> > This is one of the things which makes Linux unique
>> > in the operating system landscape: applications
>> > can target the kernel directly. Unlike in virtually
>> > every other operating system out there, the Linux kernel
>> > to user space binary interface is documented[2] as stable.
>> > Breaking it is considered a regression in the kernel.
>> > Therefore it makes sense for a compiler to target it.
>> > The same is not true for any other operating system.
>>
>> There is quite a bit of variance in how the kernel is entered. On
>> x86-64, one once popular mechanism is longer present in widely-used
>> kernels.
>
> I assume you're implicitly referencing the vsyscall mechanism, but on
> amd64 it's not useful to *enter the kernel*, right? It was useful for
> obtaining the result of certain syscalls without actually entering
> the kernel, like with vdso.
The implementation performed a standard system call if a pure userspace
implementation wasn't possible. It wasn't intended as a general-purpose
way to enter the kernel (although it could be used as such, hence the
desire to remove it in some cases).
Thanks,
Florian
next prev parent reply other threads:[~2024-04-08 11:51 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-08 9:19 Matheus Afonso Martins Moreira
2024-04-08 9:58 ` Jonathan Wakely
2024-04-08 11:59 ` Matheus Afonso Martins Moreira
2024-04-08 14:00 ` Jonathan Wakely
2024-04-08 11:24 ` Florian Weimer
2024-04-08 11:44 ` Alexander Monakov
2024-04-08 11:50 ` Florian Weimer [this message]
2024-04-08 13:01 ` Alexander Monakov
2024-04-08 13:37 ` Matheus Afonso Martins Moreira
2024-04-08 18:18 ` Paul Iannetta
2024-04-08 18:26 ` Andrew Pinski
2024-04-08 20:01 ` Paul Iannetta
2024-04-08 20:20 ` Paul Koning
2024-04-10 1:48 ` Matheus Afonso Martins Moreira
2024-04-10 13:15 ` Paul Koning
2024-04-10 14:10 ` Matheus Afonso Martins Moreira
2024-04-10 1:26 ` Matheus Afonso Martins Moreira
2024-04-08 20:24 ` Paul Floyd
2024-04-10 2:19 ` Matheus Afonso Martins Moreira
2024-04-09 11:45 ` Szabolcs Nagy
2024-04-10 2:59 ` Matheus Afonso Martins Moreira
2024-04-10 11:04 ` Szabolcs Nagy
2024-04-10 14:00 ` Matheus Afonso Martins Moreira
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