Hi Tom,
On Mon, 14 Oct 2024 at 15:55, Tom Rini trini@konsulko.com wrote:
On Mon, Oct 14, 2024 at 03:50:51PM -0600, Simon Glass wrote:
Hi Tom,
On Mon, 14 Oct 2024 at 15:42, Tom Rini trini@konsulko.com wrote:
On Mon, Oct 14, 2024 at 02:19:56PM -0600, Simon Glass wrote:
Hi,
On Fri, 11 Oct 2024 at 23:47, Ilias Apalodimas ilias.apalodimas@linaro.org wrote:
Hi Tom
On Sat, 12 Oct 2024 at 04:27, Tom Rini trini@konsulko.com wrote:
On Sat, Oct 12, 2024 at 12:01:54AM +0200, Heinrich Schuchardt wrote: > > > Am 11. Oktober 2024 23:21:25 MESZ schrieb Simon Glass sjg@chromium.org: > >The 'point of cooperation' is where U-Boot starts allowing EFI to use > >memory outside of the U-Boot region. Until that point, it is desirable > >to keep more below U-Boot free for loading images. > > > >Reserve a small region for this purpose. > > Your commit message provides no clue why this should be needed.
Yes, I hadn't realised that people didn't understand what I was getting at. Tom asked the same question on irc.
It allows us to separate the lmb allocations from the EFI allocations, so we don't need to have them both in sync. We use lmb for loading images, then EFI takes over and does what it likes, respecting the existing lmb reservations.
But, again, LMB is not for loading of images. It's for dealing with memory reservations of various types.
Up until recently, I believe, my statement was true, but in any case, this isn't gemaine to the issue here.
The point is, this is a useful distinction, allowing us to avoid the complexity of keeping them in sync, and avoid putting this pain on people who are not using EFI. We are either in U-Boot code, in which case lmb rules, or we are going into an app, in which case EFI rules (but must read in the lmb info).
We are going to end up with people turning off EFI_LOADER because it behaves so badly.
Frankly, in hind sight I should not have agreed to split the LMB rework between "everything else" and "EFI" in hopes that we would then be able to get the "EFI" part of this agreed upon. It's "behaving badly" right now because we merged half of the changes in the hopes that we could get your agreement on the rest of them fairly quickly. This is not happening, however.
Well, another option would be to revert the problem patch (or two) and do this work with careful consideration of the impacts, taking account of my architectural objections. My main concern is using U-Boot's memory like a stack. Suddenly this is 'OK' and we apparently want to update U-Boot's docs to say so. It is just not a good idea!
A good part of the reason that U-Boot solves the problems it does is that it mostly has a good design. The EFI_LOADER can be improved and it does not need to implement things in a particular way...it just needs to follow the spec. We are being far too rigid in saying that every memory allocation at every stage has to be handled the same way, etc.
That said, I did not expect the first series to cause problems. If my EFI-test series had landed then we could perhaps have added a test for this case of the app requesting a chunk of memory. My hope is for that test to grow and cover some of these areas, I hope this lmb/efi thing doesn't cause further problems and I will be looking to ensure that this code does not affect non-EFI booting negatively.
My series to solve this same problem (EFI's use of memory) have never been more than a few small patches. Please take a look at the current series[1], particularly patch 5.
Regards, Simon
[1] https://patchwork.ozlabs.org/project/uboot/list/?series=427729