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From: Arvind Sankar <nivedita@alum.mit.edu>
To: Hans de Goede <hdegoede@redhat.com>
Cc: Arvind Sankar <nivedita@alum.mit.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/2] x86/purgatory: Make sure we fail the build if purgatory.ro has missing symbols
Date: Thu, 12 Mar 2020 14:23:23 -0400	[thread overview]
Message-ID: <20200312182322.GA506594@rani.riverdale.lan> (raw)
In-Reply-To: <e96ea0cc-954d-2cd3-8d9d-53d57856d8aa@redhat.com>

On Thu, Mar 12, 2020 at 06:46:44PM +0100, Hans de Goede wrote:
> Hi,
> 
> On 3/12/20 1:10 AM, Arvind Sankar wrote:
> > On Wed, Mar 11, 2020 at 10:46:01PM +0100, Hans de Goede wrote:
> >> Since we link purgatory.ro with -r aka we enable "incremental linking"
> >> no checks for unresolved symbols is done while linking purgatory.ro.
> >>
> > 
> > Do we actually need to link purgatory with -r? We could use
> > --emit-relocs to get the relocation sections generated the way the main
> > x86 kernel does, no?
> > 
> > Eg like the below? This would avoid the double-link creating
> > purgatory.chk.
> 
> So I've changed the patch for this in my local tree over to the version
> suggested below and tested kexec with this (and I can confirm that it
> still works)
> 
> I'm wondering though if it would not be better to keep the purgatory.ro name ?  :
> 
> 1. The generated ELF binary should still be relocatable
> 2. .ro files are part of the global .gitignore settings, for the
>     new purgatory name we need to add an arch/x86/purgatory/.gitignore file
> 3. Keeping the purgatory.ro name will make the diff easier to read
> 
> Regards,
> 
> Hans
> 

No objections to the name, we can change it later to purgatory.elf or
something if we want in a separate patch.

There is one issue I noticed -- x86_64 kernel default LDFLAGS have
max-page-size=0x200000. If purgatory is linked into a real executable
this makes kexec-purgatory.o become quite large, from about 25k to just
over 4Mb.  Adding -z max-page-size=4096 to the LDFLAGS lowers this back
down to around 29k. arch/x86/entry/vdso/Makefile adds this flag too.

      reply	other threads:[~2020-03-12 18:23 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-11 21:45 [PATCH v4 0/2] x86/purgatory: Make sure we fail the build if purgatory.ro has missing symbols Hans de Goede
2020-03-11 21:46 ` [PATCH v4 1/2] x86/purgatory: Fix missing ftrace_likely_update symbol Hans de Goede
2020-03-11 21:46 ` [PATCH v4 2/2] x86/purgatory: Make sure we fail the build if purgatory.ro has missing symbols Hans de Goede
2020-03-12  0:10   ` Arvind Sankar
2020-03-12 11:31     ` Hans de Goede
2020-03-12 11:42       ` Borislav Petkov
2020-03-12 11:58         ` Hans de Goede
2020-03-12 12:50           ` Borislav Petkov
2020-03-12 13:34             ` Hans de Goede
2020-03-12 14:25               ` Borislav Petkov
2020-03-12 14:38                 ` Hans de Goede
2020-03-12 14:49                   ` Borislav Petkov
2020-03-12 14:57                     ` Hans de Goede
2020-03-12 15:12                       ` Borislav Petkov
2020-03-13  4:42             ` Arvind Sankar
2020-03-13  4:58               ` Arvind Sankar
2020-03-13  5:15                 ` Arvind Sankar
2020-03-16 18:52                 ` Nick Desaulniers
2020-03-13 10:47               ` Hans de Goede
2020-03-13 18:06               ` Borislav Petkov
2020-03-12 17:46     ` Hans de Goede
2020-03-12 18:23       ` Arvind Sankar [this message]

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