Hi Tom,
On Mon, 28 Jun 2021 at 11:27, Tom Rini trini@konsulko.com wrote:
On Mon, Jun 28, 2021 at 10:26:35AM -0600, Simon Glass wrote:
Hi Heinrich,
On Mon, 28 Jun 2021 at 09:20, Heinrich Schuchardt xypron.glpk@gmx.de wrote:
On 6/28/21 4:18 PM, Simon Glass wrote:
Hi Tom, Mark,
On Mon, 28 Jun 2021 at 07:37, Tom Rini trini@konsulko.com wrote:
On Mon, Jun 28, 2021 at 10:38:50AM +0200, Mark Kettenis wrote:
> From: Simon Glass sjg@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?
Well there is no point in having two files if one will do. Also it allows for a hash / signature check.
The question of "how great would it be and how many problems would it have solved if FIT images had become popular" is one for another time. It will always have its use cases and users but never the broad adoption many of us felt it should have. Bringing it up in this context won't change that.
I see Peter's reply below so will make time to dig into this and understand the problems with FIT better. I feel that EFI comes with all sorts of problems so I'm far from convinced, at this point. Sorry.
I'm saying this because I think there are some important technical questions within U-Boot to resolve because the EFI loader part of U-Boot is critical to our long term future. And DM is an important part of our internal design and we're (probably later than I should have) pulling out the parts that haven't been updated so that we can deliver on some of the overall promise of DM better, too.
Yes, migration has certainly been slow. As you know I mostly stopped pushing it a few years back when I saw all the reluctance. I'm very pleased you are taking that on and I think it will help a lot.
If what you say comes to pass, it is even more important that EFI is more integrated, rather than being a bolt on. Thanks largely to Heinrich, the tests are in quite good shape, so refactoring should be feasible.
Regards, Simon