linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Borislav Petkov <bp@alien8.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Kelley <mikelley@microsoft.com>,
	James Morris <jmorris@namei.org>, Sasha Levin <sashal@kernel.org>,
	Mike Rapoport <rppt@linux.ibm.com>, x86-ml <x86@kernel.org>,
	lkml <linux-kernel@vger.kernel.org>,
	James Morris <James.Morris@microsoft.com>
Subject: Re: [GIT PULL] x86/urgent for v5.13-rc5
Date: Tue, 8 Jun 2021 22:01:50 +0200	[thread overview]
Message-ID: <YL/MoOZFRwo261WG@zn.tnic> (raw)
In-Reply-To: <CAHk-=wh1nz4=72vk3+q5TuPwBF2HMY4SnBOZr6WSLp=s4KExSA@mail.gmail.com>

On Tue, Jun 08, 2021 at 12:22:50PM -0700, Linus Torvalds wrote:
> On Tue, Jun 8, 2021 at 11:33 AM Borislav Petkov <bp@alien8.de> wrote:
> >
> > Linus, maybe we should at least give it a try and see whether someone
> > complains and revert, potentially...?
> 
> I already merged the change that did that.

Oh yeah, I meant: let's leave it in and try it and only revert if there's
trouble.

> It might be worth adding a comment about the verified Windows behavior
> here, but I think otherwise we're all done.

How's that (comment re-flowed):

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 1e720626069a..b58cdc70f86b 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1084,17 +1084,18 @@ void __init setup_arch(char **cmdline_p)
 #endif
 
 	/*
-	 * Find free memory for the real mode trampoline and place it
-	 * there.
-	 * If there is not enough free memory under 1M, on EFI-enabled
-	 * systems there will be additional attempt to reclaim the memory
-	 * for the real mode trampoline at efi_free_boot_services().
+	 * Find free memory for the real mode trampoline and place it there. If
+	 * there is not enough free memory under 1M, on EFI-enabled systems
+	 * there will be additional attempt to reclaim the memory for the real
+	 * mode trampoline at efi_free_boot_services().
 	 *
-	 * Unconditionally reserve the entire first 1M of RAM because
-	 * BIOSes are know to corrupt low memory and several
-	 * hundred kilobytes are not worth complex detection what memory gets
-	 * clobbered. Moreover, on machines with SandyBridge graphics or in
-	 * setups that use crashkernel the entire 1M is reserved anyway.
+	 * Unconditionally reserve the entire first 1M of RAM because BIOSes
+	 * are known to corrupt low memory and several hundred kilobytes are not
+	 * worth complex detection what memory gets clobbered. Windows does the
+	 * same thing for very similar reasons.
+	 *
+	 * Moreover, on machines with SandyBridge graphics or in setups that use
+	 * crashkernel the entire 1M is reserved anyway.
 	 */
 	reserve_real_mode();
 

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2021-06-08 20:02 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-06  7:55 [GIT PULL] x86/urgent for v5.13-rc5 Borislav Petkov
2021-06-06 19:38 ` Linus Torvalds
2021-06-06 20:58   ` Mike Rapoport
2021-06-06 21:23     ` Linus Torvalds
2021-06-06 22:07       ` Borislav Petkov
2021-06-06 23:05         ` Sasha Levin
2021-06-07 18:46           ` James Morris
2021-06-08 17:53             ` Michael Kelley
2021-06-08 18:33               ` Borislav Petkov
2021-06-08 19:22                 ` Linus Torvalds
2021-06-08 20:01                   ` Borislav Petkov [this message]
2021-06-08 20:03                     ` Linus Torvalds
2021-06-08 20:30                       ` [PATCH] x86/setup: Document that Windows reserves the first MiB Borislav Petkov
2021-06-09  8:54                         ` Mike Rapoport
2021-06-06 20:14 ` [GIT PULL] x86/urgent for v5.13-rc5 pr-tracker-bot

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YL/MoOZFRwo261WG@zn.tnic \
    --to=bp@alien8.de \
    --cc=James.Morris@microsoft.com \
    --cc=jmorris@namei.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mikelley@microsoft.com \
    --cc=rppt@linux.ibm.com \
    --cc=sashal@kernel.org \
    --cc=torvalds@linux-foundation.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).