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Date:   Tue, 24 Oct 2023 12:14:25 -0700
From:   "H. Peter Anvin" <hpa@zytor.com>
To:     "Luck, Tony" <tony.luck@intel.com>,
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        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
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Subject: RE: [PATCH  v2 1/6] x86/bugs: Add asm helpers for executing VERW
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On October 24, 2023 11:49:07 AM PDT, "Luck, Tony" <tony=2Eluck@intel=2Ecom>=
 wrote:
>> the only overhead to modules other than load time (including the runtim=
e linking) is that modules can't realistically be mapped using large page e=
ntries=2E
>
>If there were some significant win for using large pages, couldn't the
>kernel pre-allocate some 2MB pages in the [-2GiB,0) range?  Boot paramete=
r
>for how many (perhaps two for separate code/data pages)=2E First few load=
ed
>modules get to use that space until it is all gone=2E
>
>It would all be quite messy if those modules were later unloaded/reloaded
>=2E=2E=2E so there would have to be some compelling benchmarks to justify
>the complexity=2E
>
>That's probably why Peter said "can't realistically"=2E
>
>-Tony
>

Sure it could, but it would mean the kernel is sitting on an average of 6 =
MB of unusable memory=2E It would also mean that unloaded modules would cre=
ate holes in that memory which would have to be managed=2E