From: Hanabishi <i.r.e.c.c.a.k.u.n+kernel.org@gmail.com>
To: Borislav Petkov <bp@alien8.de>, John <therealgraysky@proton.me>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Unknown <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] x86: add more x86-64 micro-architecture levels
Date: Tue, 17 Sep 2024 21:33:36 +0000 [thread overview]
Message-ID: <90d5a756-e534-490b-b451-7c855183ebc3@gmail.com> (raw)
In-Reply-To: <20240915124944.GAZubX6LAcjQjN-yEb@fat_crate.local>
On 9/15/24 12:49, Borislav Petkov wrote:
> Patches like this one appear off and on on the mailing list and each
> time I ask what's the upside of maintaining this complexity?
Besides, there are already well-known patches exist for years. So why reinventing the wheel here?
E.g. graysky patch used by ZEN kernel:
https://github.com/zen-kernel/zen-kernel/commit/6f32b8af8ccdb56ef2856db3631eea55b79378c6
It contains way more architectures, includig ISA levels.
On 9/15/24 11:05, John wrote:
> GCC 11.1 and Clang 12.0[1] allow for the following new generic
> 64-bit levels: x86-64-v2, x86-64-v3, and x86-64-v4. This commit
> adds them as options accessible under:
> Processor type and features --->
> Processor family --->
Anyway, this whole thing is actually more complicated than simply setting '-march'.
Vector instructions are known to be problematic for the kernel, so they are disabled by KBUILD_CFLAGS.
If you want to go with higher ISA levels than the kernel expects, an additional patch like this is required:
https://github.com/zen-kernel/zen-kernel/commit/addc601c58e035e28153deeb6d441b91f1a50247
next prev parent reply other threads:[~2024-09-17 21:33 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-15 11:05 [PATCH] x86: add more x86-64 micro-architecture levels John
2024-09-15 11:40 ` Dave Hansen
2024-09-15 12:25 ` John
2024-09-15 12:58 ` Dave Hansen
2024-09-15 18:42 ` John
2024-09-17 18:22 ` John
2024-09-17 18:45 ` H. Peter Anvin
2024-09-15 12:49 ` Borislav Petkov
2024-09-15 12:53 ` Dave Hansen
2024-09-17 21:33 ` Hanabishi [this message]
2024-09-18 19:02 ` John
2024-09-18 20:25 ` Hanabishi
2024-09-18 21:14 ` John
2024-09-18 21:48 ` Hanabishi
2024-09-18 23:07 ` John
2024-09-16 5:14 ` WangYuli
2024-09-24 7:00 ` kernel test robot
2024-09-24 13:38 ` Dave Hansen
2024-09-24 17:40 ` John
2024-09-26 1:43 ` Oliver Sang
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