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[82.27.104.80]) by smtp.gmail.com with ESMTPSA id i33sm3189489wri.79.2020.10.23.05.47.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Oct 2020 05:47:12 -0700 (PDT) Date: Fri, 23 Oct 2020 13:47:10 +0100 From: Leif Lindholm To: Ard Biesheuvel Cc: linux-efi@vger.kernel.org, grub-devel@gnu.org, daniel.kiper@oracle.com Subject: Re: [PATCH 4/4] linux: ignore FDT unless we need to modify it Message-ID: <20201023124710.GD1664@vanye> References: <20201023120825.30466-1-ard.biesheuvel@arm.com> <20201023120825.30466-5-ard.biesheuvel@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201023120825.30466-5-ard.biesheuvel@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Fri, Oct 23, 2020 at 14:08:25 +0200, Ard Biesheuvel wrote: > Now that we implemented supported for the LoadFile2 protocol for initrd > loading, there is no longer a need to pass the initrd parameters via > the device tree. This means there is no longer a reason to update the > device tree in the first place, and so we can ignore it entirely. There is a change in behaviour here which I don't think matters, but I'll call it out anyway: If there was ever a kernel out there with an EFI stub that depended on a chosen node existing in the DT, and the one provide by firmware did not contain one, that setup would break from this *if* it didn't use an initrd. / Leif > The only remaining reason to deal with the devicetree is if we are > using the 'devicetree' command to load one from disk, so tweak the > logic in grub_fdt_install() to take that into account. > > Signed-off-by: Ard Biesheuvel > --- > grub-core/loader/arm64/linux.c | 22 ++++++++++---------- > grub-core/loader/efi/fdt.c | 7 +++++-- > 2 files changed, 16 insertions(+), 13 deletions(-) > > diff --git a/grub-core/loader/arm64/linux.c b/grub-core/loader/arm64/linux.c > index 285422c7bd43..9e282b6660fe 100644 > --- a/grub-core/loader/arm64/linux.c > +++ b/grub-core/loader/arm64/linux.c > @@ -93,21 +93,21 @@ finalize_params_linux (void) > > void *fdt; > > - fdt = grub_fdt_load (GRUB_EFI_LINUX_FDT_EXTRA_SPACE); > + /* Set initrd info */ > + if (initrd_start && initrd_end > initrd_start) > + { > + fdt = grub_fdt_load (GRUB_EFI_LINUX_FDT_EXTRA_SPACE); > > - if (!fdt) > - goto failure; > + if (!fdt) > + goto failure; > > - node = grub_fdt_find_subnode (fdt, 0, "chosen"); > - if (node < 0) > - node = grub_fdt_add_subnode (fdt, 0, "chosen"); > + node = grub_fdt_find_subnode (fdt, 0, "chosen"); > + if (node < 0) > + node = grub_fdt_add_subnode (fdt, 0, "chosen"); > > - if (node < 1) > - goto failure; > + if (node < 1) > + goto failure; > > - /* Set initrd info */ > - if (initrd_start && initrd_end > initrd_start) > - { > grub_dprintf ("linux", "Initrd @ %p-%p\n", > (void *) initrd_start, (void *) initrd_end); > > diff --git a/grub-core/loader/efi/fdt.c b/grub-core/loader/efi/fdt.c > index ee9c5592c700..ab900b27d927 100644 > --- a/grub-core/loader/efi/fdt.c > +++ b/grub-core/loader/efi/fdt.c > @@ -85,13 +85,16 @@ grub_fdt_install (void) > grub_efi_guid_t fdt_guid = GRUB_EFI_DEVICE_TREE_GUID; > grub_efi_status_t status; > > + if (!fdt && !loaded_fdt) > + return GRUB_ERR_NONE; > + > b = grub_efi_system_table->boot_services; > - status = b->install_configuration_table (&fdt_guid, fdt); > + status = b->install_configuration_table (&fdt_guid, fdt ?: loaded_fdt); > if (status != GRUB_EFI_SUCCESS) > return grub_error (GRUB_ERR_IO, "failed to install FDT"); > > grub_dprintf ("fdt", "Installed/updated FDT configuration table @ %p\n", > - fdt); > + fdt ?: loaded_fdt); > return GRUB_ERR_NONE; > } > > -- > 2.17.1 >