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From: Lennart Poettering <mzxreary@0pointer.de>
To: Jan Hendrik Farr <kernel@jfarr.cc>
Cc: Jarkko Sakkinen <jarkko@kernel.org>,
	linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
	x86@kernel.org, tglx@linutronix.de, dhowells@redhat.com,
	vgoyal@redhat.com, keyrings@vger.kernel.org,
	akpm@linux-foundation.org, Baoquan He <bhe@redhat.com>,
	bhelgaas@google.com, Luca Boccassi <bluca@debian.org>
Subject: Re: [PATCH 0/1] x86/kexec: UKI support
Date: Thu, 14 Sep 2023 10:48:55 +0200	[thread overview]
Message-ID: <ZQLI92sQrnTC9Wel@gardel-login> (raw)
In-Reply-To: <9580df76-c143-4077-8a39-b1fcc0ed37bd@app.fastmail.com>

On Di, 12.09.23 17:32, Jan Hendrik Farr (kernel@jfarr.cc) wrote:

> >> The format itself is rather simple. It's just a PE file (as required
> >> by the UEFI spec) that contains a small stub application in the .text,
> >> .data, etc sections that is responsible for invoking the contained
> >> kernel and initrd with the contained cmdline. The kernel image is
> >> placed into a .kernel section, the initrd into a .initrd section, and
> >> the cmdline into a .cmdline section in the PE executable.
> >
> > How does this interact with the existing EFI stub support in
> > linux?
>
> It doesn't. During normal boot of a UKI the stub in it is used
> (systemd-stub, see:
> https://www.freedesktop.org/software/systemd/man/systemd-stub.html). The
> kernel's own EFI stub will still be in the binary inside the .linux
> section but not used.

That's not true actually, if the inner kernel supports the EFI stub
then systemd-stub actually defers to that for kernel execution. It's
more portable that way, since the kernel then deals with the
differences in the boot protocol on different architectures.

Lennart

--
Lennart Poettering, Berlin

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WARNING: multiple messages have this Message-ID (diff)
From: Lennart Poettering <mzxreary@0pointer.de>
To: Jan Hendrik Farr <kernel@jfarr.cc>
Cc: Jarkko Sakkinen <jarkko@kernel.org>,
	linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
	x86@kernel.org, tglx@linutronix.de, dhowells@redhat.com,
	vgoyal@redhat.com, keyrings@vger.kernel.org,
	akpm@linux-foundation.org, Baoquan He <bhe@redhat.com>,
	bhelgaas@google.com, Luca Boccassi <bluca@debian.org>
Subject: Re: [PATCH 0/1] x86/kexec: UKI support
Date: Thu, 14 Sep 2023 10:48:55 +0200	[thread overview]
Message-ID: <ZQLI92sQrnTC9Wel@gardel-login> (raw)
In-Reply-To: <9580df76-c143-4077-8a39-b1fcc0ed37bd@app.fastmail.com>

On Di, 12.09.23 17:32, Jan Hendrik Farr (kernel@jfarr.cc) wrote:

> >> The format itself is rather simple. It's just a PE file (as required
> >> by the UEFI spec) that contains a small stub application in the .text,
> >> .data, etc sections that is responsible for invoking the contained
> >> kernel and initrd with the contained cmdline. The kernel image is
> >> placed into a .kernel section, the initrd into a .initrd section, and
> >> the cmdline into a .cmdline section in the PE executable.
> >
> > How does this interact with the existing EFI stub support in
> > linux?
>
> It doesn't. During normal boot of a UKI the stub in it is used
> (systemd-stub, see:
> https://www.freedesktop.org/software/systemd/man/systemd-stub.html). The
> kernel's own EFI stub will still be in the binary inside the .linux
> section but not used.

That's not true actually, if the inner kernel supports the EFI stub
then systemd-stub actually defers to that for kernel execution. It's
more portable that way, since the kernel then deals with the
differences in the boot protocol on different architectures.

Lennart

--
Lennart Poettering, Berlin

  parent reply	other threads:[~2023-09-14  8:57 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-09 16:18 [PATCH 0/1] x86/kexec: UKI support Jan Hendrik Farr
2023-09-09 16:18 ` Jan Hendrik Farr
2023-09-09 16:18 ` [PATCH 1/1] " Jan Hendrik Farr
2023-09-09 16:18   ` Jan Hendrik Farr
2023-09-09 17:15 ` [PATCH 0/1] " Luca Boccassi
2023-09-09 17:15   ` Luca Boccassi
2023-09-09 17:57   ` Jan Hendrik Farr
2023-09-09 17:57     ` Jan Hendrik Farr
2023-09-09 18:10     ` Luca Boccassi
2023-09-09 18:10       ` Luca Boccassi
2023-09-11  3:23       ` Jan Hendrik Farr
2023-09-11  3:23         ` Jan Hendrik Farr
2023-09-11 22:02 ` Jarkko Sakkinen
2023-09-11 22:02   ` Jarkko Sakkinen
2023-09-11 22:54   ` Jan Hendrik Farr
2023-09-11 22:54     ` Jan Hendrik Farr
2023-09-12 10:33     ` Jarkko Sakkinen
2023-09-12 10:33       ` Jarkko Sakkinen
2023-09-12 15:32       ` Jan Hendrik Farr
2023-09-12 15:32         ` Jan Hendrik Farr
2023-09-12 17:41         ` Jarkko Sakkinen
2023-09-12 17:41           ` Jarkko Sakkinen
2023-09-12 18:56           ` Jan Hendrik Farr
2023-09-12 18:56             ` Jan Hendrik Farr
2023-09-12 19:24             ` Jarkko Sakkinen
2023-09-12 19:24               ` Jarkko Sakkinen
2023-09-12 19:38               ` Jan Hendrik Farr
2023-09-12 19:38                 ` Jan Hendrik Farr
2023-09-12 20:49               ` Jan Hendrik Farr
2023-09-12 20:49                 ` Jan Hendrik Farr
2023-09-13 14:45                 ` Jarkko Sakkinen
2023-09-13 14:45                   ` Jarkko Sakkinen
2023-09-13 15:07                   ` Jan Hendrik Farr
2023-09-13 15:07                     ` Jan Hendrik Farr
2023-09-13 15:58                     ` Jarkko Sakkinen
2023-09-13 15:58                       ` Jarkko Sakkinen
2023-09-14  9:11                   ` Lennart Poettering
2023-09-14  9:11                     ` Lennart Poettering
2023-09-14 12:12                     ` Jarkko Sakkinen
2023-09-14 12:12                       ` Jarkko Sakkinen
2023-09-14  8:48         ` Lennart Poettering [this message]
2023-09-14  8:48           ` Lennart Poettering
2023-09-14 11:52           ` Jarkko Sakkinen
2023-09-14 11:52             ` Jarkko Sakkinen
2023-09-11 23:20   ` [systemd-devel] " Neal Gompa
2023-09-11 23:20     ` Neal Gompa
2023-09-12 10:37     ` Jarkko Sakkinen
2023-09-12 10:37       ` Jarkko Sakkinen
2023-09-18 15:41       ` Dimitri John Ledkov
2023-09-18 15:41         ` Dimitri John Ledkov
2023-09-25 16:43         ` Jarkko Sakkinen
2023-09-25 16:43           ` Jarkko Sakkinen

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