On Fri, 2017-03-24 at 23:40 +0100, Alexander Graf wrote:
On 24/03/2017 23:22, Marcel Ziswiler wrote:
Hi Alexander
On Tue, 2017-03-21 at 14:50 +0100, Alexander Graf wrote:
On 21/03/2017 14:37, Marcel Ziswiler wrote:
Hi Alex
On Tue, 2017-03-21 at 10:46 +0100, Alexander Graf wrote:
On 21/03/2017 10:29, Marcel Ziswiler wrote:
This series adds support for the Toradex Apalis TK1 and introduces a new option to disable the external clock loopback on SDMMC3.
The whole series is also available here:
http://git.toradex.com/cgit/u-boot-toradex.git/log/?h=for-n ext
Changes in v4:
- Re-based.
- Drop patches 2 and 3:
mmc: tegra: move CONFIG_TEGRA_MMC from headers to defconfigs mmc: tegra: introduce CONFIG_TEGRA_MMC to Kconfig in favor of commit 1d2c0506d31a9997e5ffc22e90942902f673b107 mmc: move more driver config options to Kconfig from Masahiro.
- Meld patch 6
apalis-tk1: clean-up defconfig into first one.
- Add distro boot fallback.
- Enable FIT and device tree overlay support.
- Explicitly drop EFI loader support.
Any particular reason for this?
Yes, a waste of 20K which on some of our modules is rather crucial. I personally think force enabling EFI for everything was not too smart an idea but whatever.
Well, it's enabled by default for a good reason: Compatibility.
While I do agree about compatibility I don't quite see what this has to do with EFI. I personally don't believe the BIOS/EFI disaster of the x86 world is worth copying to ARM, sorry. Other distributions like Fedora e.g. achieve the same with distro boot isn't it? After all isn't
Fedora uses extlinux for 32bit ARM and UEFI for 64bit ARM. The main reason they're using extlinux is that at the point in time when they standardized on it as their preferred booting method, the UEFI implementation didn't exist yet.
It probably also will never work across all 32-bit ARM variants available out there.
the device tree the agreed upon hardware description in the ARM world?
Yes, device tree is very much agree upon as hardware description! And with UEFI nothing changes in that regard. We still use device tree by default and unless you're really into shooting yourself into your own feet I don't see why you'd want to do it any differently.
This is not an ACPI vs DT discussion. It's really just about the question which entity controls selection and handover into the kernel.
With UEFI it's much easier to implement snapshot booting for example, because you can move all of that logic into a platform agnostic piece of code. It's the only supported way to have KASLR work on arm64. It allows for boot selection logic (A/B fallback for example) in something outside of a boot script or your boot loader sources, so that code stays reusable.
Another area which probably will never generically work across all hardware just because there are simply too many hardware variants out there in the 32-bit ARM world.
Take a look at my video at ELC for some rationale behind it:
Yes, I have seen that one before and we were shaking our heads. But maybe it really is the way to go just like systemd is now ruling the world (;-p).
I want to move to a world where people can just take a random distribution and expect it to work, rather than waste weeks over weeks on fiddling around with random BSPs that nobody really wants only to realize 2 years down the road that their security footprint is en par with a swiss cheese.
Hey, nothing against Swiss cheese! And BTW the term Swiss cheese is about as nonsense as the term Linux. There is really a huge collection of different Swiss cheeses... Sorry, I just do get upset at times if certain countries gastronomy people do ask whether I want my sandwich with Swiss cheese wondering what they mean by that. But I guess those chaps now do have their very own issues (;-p).
:)
It's also the preferred option to boot BSD for example.
So how bad are the 20k for you? In fact, I'm surprised it's 20k at all - it used to be 10k. The overhead of DM should be much higher and I doubt you want to disable that ;). Usually a full U-Boot build is ~500k, so even at 20k we're talking about 4% - less than a compiler update usually gets you.
If size really is such a big concern, moving to THUMB code is going to buy you much more in storage savings than dropping (quite useful) UEFI support.
If however there are real technical issues with it, I'm happy to hear them and fix them as far as possible.
The technical issue is that I still don't quite see why U-Boot needs EFI. I stopped using SuSE more than 15 years ago and never regretted
For 32bit ARM it doesn't really "need" it. If you feel terribly strongly about it, I don't have hard feelings with leaving it out. But if it's really just a matter of taste rather than technical merit, I'd rather prefer to have the option available for users. The same reason you usually want to have distro boot support enabled and not just a hardcoded bootcmd line.
Uups, we still have it kind of hard coded by default but at least with a distro boot fall back.
it, no pun intended.
But if it is really agreed upon mandatory to enable it I am happy to do so as I would love to finally get that thing in after an almost 4 months endeavour.
I'm not nacking this patch set, even with EFI_LOADER disabled. But I think that if there's no good reason to disable the feature, we should leave it enabled.
OK, I will send a V5 which does not explicitly disable it.
And if you really are size constrained with today's configuration, please enable thumb2, otherwise you will get bitten on random compiler updates down the road.
Unfortunately the platforms I have that are space constrained do not support any such but again those probably won't ever run any regular distro neither.
Thanks,
Thank you.
Alex
Cheers
Marcel