linux-kernel - Re: [PATCH] um: Remove 3-level page table support on i386

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Message-ID: <627bd11a7fe69fed02719c2ecf5370b59328e80d.camel@sipsolutions.net>
Date: Thu, 19 Sep 2024 09:22:19 +0200
From: Benjamin Berg <benjamin@...solutions.net>
To: Johannes Berg <johannes@...solutions.net>, Tiwei Bie
	 <tiwei.btw@...group.com>, richard@....at, anton.ivanov@...bridgegreys.com
Cc: linux-um@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] um: Remove 3-level page table support on i386

On Thu, 2024-09-19 at 08:54 +0200, Johannes Berg wrote:
> On Wed, 2024-09-18 at 14:17 +0800, Tiwei Bie wrote:
> > The highmem support has been removed by commit a98a6d864d3b ("um:
> > Remove broken highmem support"). The 2-level page table is
> > sufficient
> > on UML/i386 now. Remove the 3-level page table support on UML/i386
> > which is still marked as experimental.
> > 
> 
> No real objection, but with the 4-level page table work on 64-bit
> pending as well (which likely conflicts), I wonder if we should just
> remove 3-level *entirely*?

Fine with me. There is only the tiny advantage of saving a few pages of
memory for each process. I just erred on the side of keeping it in case
anyone is cares to the option …

I'll resubmit the patchset without 3-level support then, possibly on
top of this patch. On the assumption that no one actually cares about
3-level page tables on x86_64.

Benjamin