From: Borislav Petkov <bp@alien8.de>
To: Juergen Gross <jgross@suse.com>
Cc: xen-devel@lists.xenproject.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v2 02/10] x86/mtrr: remove unused cyrix_set_all() function
Date: Thu, 25 Aug 2022 13:42:16 +0200 [thread overview]
Message-ID: <YwdgGFJWTV1YF3n2@zn.tnic> (raw)
In-Reply-To: <aff049cb-ebdd-68ad-5597-d22f87026297@suse.com>
On Thu, Aug 25, 2022 at 12:41:05PM +0200, Juergen Gross wrote:
> Maybe the alternative reasoning is much faster to understand: if the
> Cyrix set_all() could be called, the AMD and Centaur ones would be callable,
> too.
Right.
> Those being called would result in a NULL deref, so why should we keep
> the Cyrix one?
I know you're eager to remove dead code - I'd love that too. But before
we do that, we need to find out whether some Cyrix hw out there would
not need this.
I know, I know, they should've complained by now ... maybe they have but
we haven't heard about it.
What it most likely looks like is that those machines - a commit from
before git
commit 8fbdcb188e31ac901e216b466b97e90e8b057daa
Author: Dave Jones <davej@suse.de>
Date: Wed Aug 14 21:14:22 2002 -0700
[PATCH] Modular x86 MTRR driver.
talks about
+/*
+ * On Cyrix 6x86(MX) and M II the ARR3 is special: it has connection
+ * with the SMM (System Management Mode) mode. So we need the following:
+ * Check whether SMI_LOCK (CCR3 bit 0) is set
+ * if it is set, write a warning message: ARR3 cannot be changed!
+ * (it cannot be changed until the next processor reset)
which sounds like old rust. And which no one uses or such machines are
long dead already.
Wikipedia says:
https://en.wikipedia.org/wiki/Cyrix_6x86
"The Cyrix 6x86 is a line of sixth-generation, 32-bit x86
microprocessors designed and released by Cyrix in 1995..."
So I'm thinking removing it would be ok...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-08-25 11:42 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-20 9:25 [PATCH v2 00/10] x86: make pat and mtrr independent from each other Juergen Gross
2022-08-20 9:25 ` [PATCH v2 01/10] x86/mtrr: fix MTRR fixup on APs Juergen Gross
2022-08-20 10:28 ` Greg KH
2022-08-21 12:25 ` Borislav Petkov
2022-08-21 21:41 ` Borislav Petkov
2022-08-22 5:17 ` Juergen Gross
2022-08-22 8:28 ` Borislav Petkov
2022-08-22 8:32 ` Juergen Gross
2022-10-19 18:45 ` [tip: x86/cpu] x86/mtrr: Add comment for set_mtrr_state() serialization tip-bot2 for Juergen Gross
2022-08-20 9:25 ` [PATCH v2 02/10] x86/mtrr: remove unused cyrix_set_all() function Juergen Gross
2022-08-25 10:31 ` Borislav Petkov
2022-08-25 10:38 ` Juergen Gross
2022-08-25 10:41 ` Juergen Gross
2022-08-25 11:42 ` Borislav Petkov [this message]
2022-08-25 12:13 ` Juergen Gross
2022-08-20 9:25 ` [PATCH v2 03/10] x86/mtrr: replace use_intel() with a local flag Juergen Gross
2022-08-20 9:25 ` [PATCH v2 04/10] x86: move some code out of arch/x86/kernel/cpu/mtrr Juergen Gross
2022-08-20 9:25 ` [PATCH v2 05/10] x86/mtrr: split generic_set_all() Juergen Gross
2022-08-20 9:25 ` [PATCH v2 06/10] x86/mtrr: remove set_all callback from struct mtrr_ops Juergen Gross
2022-08-20 9:25 ` [PATCH v2 07/10] x86/mtrr: simplify mtrr_bp_init() Juergen Gross
2022-08-20 9:25 ` [PATCH v2 08/10] x86/mtrr: let cache_aps_delayed_init replace mtrr_aps_delayed_init Juergen Gross
2022-08-20 9:25 ` [PATCH v2 09/10] x86/mtrr: add a stop_machine() handler calling only cache_cpu_init() Juergen Gross
2022-08-20 9:25 ` [PATCH v2 10/10] x86: decouple pat and mtrr handling Juergen Gross
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