On 6/28/21 4:18 PM, Simon Glass wrote: > Hi Tom, Mark, > > On Mon, 28 Jun 2021 at 07:37, Tom Rini <tr...@konsulko.com> wrote: >> >> On Mon, Jun 28, 2021 at 10:38:50AM +0200, Mark Kettenis wrote: >>>> From: Simon Glass <s...@chromium.org> >>>> Date: Sun, 27 Jun 2021 19:48:34 -0600 >>>> >>>> It has come to light that EFI_LOADER adds an extraordinary amount of >>>> code to U-Boot. For example, with nokia_rx51 the size delta is about >>>> 90KB. About 170 boards explicitly disable the option, but is is clear >>>> that many more could, thus saving image size and boot time. >>> >>> EFI_LOADER used to be a lot smaller. It is great to see that over the >>> years UEFI support has become more complete, but a lot of that new >>> code implements features that are not at all essential for just >>> booting an OS from storage. If that growth leads to the suggestion to >>> disable EFI_LOADER completely by default, we're putting the cart >>> before the horse. >> >> Well, I see I forgot to prefix my patch with RFC, but I hadn't found >> EFI_LOADER being used in the wild on armv7, but wasn't sure about the >> BSD families. I did see that Debian doesn't use it, and that Armbian >> doesn't even use it on aarch64. >> >>>> The current situation is affecting U-Boot's image as a svelt bootloader. >>> >>> Really? I know UEFI has a bad reputation in the Open Source world, >>> and some of its Microsoft-isms are really annoying (yay UCS-2). But >>> it works, it provides a standardized approach across several platforms >>> (ARMv7, AMRv8, RISC-V) and the industry seems to like it. Personally >>> I'd wish the industry had standardized on Open Firmware instead, but >>> that ship sailed a long time ago... >>> >>> I find it hard to imagine that 90k is a serious amount of storage for >>> something that is going to include a multi-MB Linux kernel. This >>> isn't code that lives in SPL or TPL where severe size restrictions >>> apply. >> >> In one of those cases where I need to pop back in to the other (Nokia >> N900 specific) thread and see if the big size reduction really was just >> disabling EFI_LOADER, it's perhaps just one of those "fun" things about >> Kconfig and anything other than "make oldconfig" for spotting new config >> options that default to enabled. > > Yes it will be interesting to see what you find there. My results on > nokia_rx51 were something like this: > > default > arm: (for 1/1 boards) all +129370.0 bss +1136.0 data +7399.0 > rodata +10989.0 text +109846.0 > > without ebbr > arm: (for 1/1 boards) all +38460.0 bss +1040.0 data +2375.0 > rodata +5333.0 text +29712.0 > > with various other things: > CONFIG_OF_LIBFDT_ASSUME_MASK=7 > # CONFIG_OF_TRANSLATE is not set > # CONFIG_SIMPLE_BUS is not set > # CONFIG_TI_SYSC is not set > # CONFIG_CMD_FDT is not set > > arm: (for 1/1 boards) all +19170.0 bss -16.0 data +360.0 rodata > +3274.0 text +15552.0 > > (Mark, in the same email:) >>> FIT simply isn't fit for purpose (pun intended). It only really works >>> for booting Linux, and forces people to combine u-boot, kernel, >>> initial ramdisk and other firmware components into a single image. >>> That is really undesirable as: >>> - This makes it sigificantly harder to update individual components of >>> such an image. Making it hard to update a kernel is obviously a >>> serious security risk. >>> - This makes it impossible to build an OS install image that works om >>> multiple boards/SoCs. > > > I would really like to understand this better. The whole thing is a > complete mystery to me. > > Firstly I have sometimes fiddled with booting other OSes using FIT. It > seemed OK. I can't see why it only works with Linux. > > Secondly, I don't expect that U-Boot itself would be in the FIT. > > Thirdly, do you really want the kernel and initrd to be separate? At > least in the systems I have used, they are built together, even having > the same name, e.g.: > > initrd.img-5.10.40-1rodete1-amd64 > System.map-5.10.40-1rodete1-amd64 > vmlinuz-5.10.28-1rodete2-amd64
I have not hit any distro that builds FIT images. All install vmlinux and initrd as separate files. Why would you want to change that? > > Finally, for the firmware components, do you mean system firmware? If > so, I would expect it to be more convenient to distribute updates to > that separately, although I suppose they could be combined with the > kernel if the combinatorial explosion can be contained. What is the > problem, exactly? (If you mean peripheral firmware, I would expect > fwupd to handle that.) > > What exactly is impossible? Can you please be more specific? > > FIT is just a container. It seems to have been rejected by the EFI > crew at some point. Perhaps I just need to try to use it with one of > the distros out there, to actually understand what is going on here. > But any help is appreciated. FIT and EFI are orthogonal. A FIT image can contain an EFI binary. See CONFIG_BOOTM_EFI. > >> >>>> EFI_LOADER is required by EBBR, a new boot standard which aims to >>>> bring in UEFI protocols to U-Boot. But EBRR is not required for >>>> booting. U-Boot already provides support for FIT, the 'bootm' command >>>> and a suitable hand-off to Linux. EBRR has made the decision to create >>>> a parallel infrastructure, e.g. does not use FIT, nor U-Boot's signing >>>> infrastructure. >>> >>> EFI_LOADER is required to boot FreeBSD and OpenBSD on several >>> platforms as well as generic Linux distros. For example >>> OpenBSD/armv7, OpenBSD/arm64 and OpenBSD/riscv64 all rely on >>> EFI_LOADER to boot and have done so for the last 4 years. The fact >>> that ARM has embraced UEFI as an embedded boot standard and branded it >>> EBBR really isn't all that relevant. >> >> To be clear here, I like EFI_LOADER. I too do wish some other >> technologies had become dominant for technical rather than inertia >> reasons, but here we are. Having played around with it on aarch64, >> there are some pretty nice comes-along-with parts to it. >> >> What I hadn't seen, and am only a little skeptical of still, is how far >> backwards in generations it's going to be used on. The general wish is >> that users nor off the shelf OS groups need to rebuild U-Boot for a >> given board, and instead it just works. The number of new designs for >> 32bit parts is no where near the number of new designs for 64bit parts. >> So what we're seeing in U-Boot now is people updating support on their >> older designs, and not necessarily caring about using EFI_LOADER. > > In a reply to one of the patches in this series, Heinrich mentions a > few problems that need resolving (devices for partitions and file > handles). Both of those features should first be added to U-Boot, so > EFI can then use that support. In general, EFI has tried to work > beside driver model, creating its own parallel tables, etc. Could you, please, be a bit more specific. Please, indicate which data structures you would like to integrate into the driver model. EDK II shows that a driver model completely based on UEFI protocols is possible. As long as we don't follow that road we will have separate APIs for the UEFI world and U-Boot's internal use and we will have to keep track of objects that exist only in the one world or the other. What we definitively need is a better integration between probing and removing U-Boot devices and their representation in the UEFI world. Another area that might deserve attention is memory allocation. AllocatePool() consuming whole memory pages is quite a waste. > I have > tried to influence this at various points along the way, including at > the start and I'm happy to dig out those threads if it helps. But I > wasn't kidding. it really needs to be addressed. I would love to see > Linaro (for example) organise something here and take this on. I am > very happy to help. The starting point would be comparing the DM and UEFI object models and pointing out which objects can be mapped and which cannot. Best regards Heinrich
