From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Graf Date: Mon, 11 Jun 2018 09:34:42 +0200 Subject: [U-Boot] [PATCH 14/18] efi: stub: Pass EFI GOP information to U-Boot payload In-Reply-To: References: <1528637118-32739-1-git-send-email-bmeng.cn@gmail.com> <1528637118-32739-15-git-send-email-bmeng.cn@gmail.com> <87a37e86-3d45-1f1c-92ef-422893b381ec@suse.de> Message-ID: <95f403de-6ae3-4243-dbb9-128b97c8bb04@suse.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 06/11/2018 08:01 AM, Bin Meng wrote: > Hi Alex, > > On Mon, Jun 11, 2018 at 1:52 PM, Alexander Graf wrote: >> >> On 11.06.18 01:29, Bin Meng wrote: >>> On Mon, Jun 11, 2018 at 3:16 AM, Alexander Graf wrote: >>>> >>>> On 10.06.18 15:25, Bin Meng wrote: >>>>> If UEFI BIOS has the graphics output protocol (GOP), let's pass its >>>>> information to U-Boot payload so that U-Boot can utilize it (eg: >>>>> an EFI framebuffer driver). >>>>> >>>>> Signed-off-by: Bin Meng >>>> Why can't the FB drive determine all of this on its own and just fail >>>> probe if no GOP protocol can be found? >>>> >>> It cannot. Once U-Boot payload is running, the boot services are gone. >>> There is no way to determine the GOP protocol. >> Interesting. Is there a particular reason you're not preserving boot >> services? >> > This is EFI payload support with CONFIG_EFI_STUB. Preserving boot > services is EFI application, with CONFIG_EFI_APP. For example, see > serial_efi.c which is the serial driver that uses EFI's boot services > to output characters on the serial port. Oh, I see. That makes sense now. Do people actually need CONFIG_EFI_STUB then? > >> It might be quite handy to reuse UEFI block interfaces for example. It >> might also be useful to preserve (parts of?) the memory map so we don't >> overwrite random SMM code for example. >> >> Maybe I misunderstand the purpose of the UEFI U-Boot support though ;). > Looks there is some misunderstanding around the EFI payload support. Yes, I have to admit that I never really cared enough about it to read its documentation though :). Alex