Messages in this thread | | | Date | Thu, 25 Aug 2022 13:42:16 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v2 02/10] x86/mtrr: remove unused cyrix_set_all() function |
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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
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