On Tue, 11 Dec 2018 at 10:23, Pankaj Bansal <pankaj.bansal@xxxxxxx> wrote: > > > > > -----Original Message----- > > From: Ard Biesheuvel [mailto:ard.biesheuvel@xxxxxxxxxx] > > Sent: Tuesday, December 11, 2018 2:48 PM > > To: Pankaj Bansal <pankaj.bansal@xxxxxxx> > > Cc: Mark Rutland <mark.rutland@xxxxxxx>; Leif Lindholm > > <leif.lindholm@xxxxxxxxxx>; Grant Likely <grant.likely@xxxxxxx>; Varun Sethi > > <V.Sethi@xxxxxxx>; Udit Kumar <udit.kumar@xxxxxxx>; Bhupesh Sharma > > <bhsharma@xxxxxxxxxx>; linux-efi <linux-efi@xxxxxxxxxxxxxxx> > > Subject: Re: [PATCH v2 2/2] drivers: firmware: efi: install new fdt in > > configuration table > > > > On Tue, 11 Dec 2018 at 10:04, Pankaj Bansal <pankaj.bansal@xxxxxxx> wrote: > > > > > > Bootloader may need to fixup the device tree before OS can use it. > > > > > > Therefore, install fdt used by OS in configuration tables and > > > associate it with device tree guid. > > > > > > UEFI/DXE drivers can fixup this device tree in their respective > > > ExitBootServices events. > > > > > > Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > > > Cc: linux-efi@xxxxxxxxxxxxxxx > > > Signed-off-by: Pankaj Bansal <pankaj.bansal@xxxxxxx> > > > > I still think this is a bad idea. The firmware is closely tied to the platform, so it > > should provide the DT instead of the kernel. > > It is. It's just that firmware is responsible to fix the status of devices before kernel > can use those. In efi stub, the fdt is copied into new_fdt before exit boot services. > We need to fix the status of devices as part of exit boot services. We cannot do it > before, because firmware is using these device and they are not ready for kernel to use yet. > That doesn't matter. The kernel will not use devices from the DT before ExitBootServices() anyway.
