On Tue, 16 Jun 2026 at 12:39, Ludwig Nussel <[email protected]> wrote: > > On 6/15/26 15:25, Ilias Apalodimas wrote: > > On Mon, 15 Jun 2026 at 16:09, Ilias Apalodimas > > <[email protected]> wrote: > >> > >> Hi Ludwig, > >> > >> [...] > >> > >>>>>> > >>>>>> I'd like the eventlog to be initialized before calling this (look > >>>>>> below). > >>>>> > >>>>> What if I removed the log parameter from those tcg2_* functions instead? > >>>>> The event log belongs to the tpm device IMO, so should be initialized > >>>>> with the device. > >>>> > >>>> Measured boot EventLogs etc are primarily described by the TCG specs & > >>>> EFI and we only have a specification for it there. The DT describes on > >>>> how to pass it over to linux with sml-base etc. > >>>> However, in the EFI case the Eventlog is allocated as ACPI memory. So > >>>> you cannot allocate the EventLog a priori, until you figure out what > >>>> method you are using to boot. We also have use cases people using it > >>>> only for RNG, due to limited memory, so we can't just allocate it on > >>>> the device bringup. And lastly... Some first stage bootloaders do not > >>>> initialize the TPM & drivers. What they do is prepare an EventLog and > >>>> expect U-Boot to replay it once the TPM is up and running. In that > >>>> case we obviously need to preserve what we have instead of starting > >>>> from scratch. > >>> > >>> Ack, we are on the same page here. > >>> > >>>> My main concern is that I *don't* want the EFI and non-EFI code to > >>>> deviate. I have some patches that I am playing around for quite some > >>>> time and rebased them last week for this reason [1]. If you think > >>>> those help your use case or make your life easier feel free to include > >>>> them. > >>> > >>> Good idea and orthogonal to what I am doing I think. This duplication in > >>> EFI stressed my brain too but I can't care about EFI right now :-) > >> > >> It is, but the deviation in EFI is pretty minimal atm. > >> - EFI calls tcg2_log_prepare_buffer instead of tcg2_measurement_init() > >> -- That's what my patches fix > >> - EFI has it's own version of tcg2_measure_event() -- That's easy to > >> fix as well,. > >> > >>> > >>> IIUC you are centering the change around calling > >>> tcg2_log_prepare_buffer() in efi_init_event_log(). What do you think > >>> about aiming for tcg2_measurement_init() as central starting point > >>> instead? > >>> That would allow to remove even more duplicated code. > >>> It should be sufficient to have tcg2_measurement_init() accept an > >>> optional pointer to pre-allocated log buffer memory. Attached patch > >>> maybe explains the idea better (just as idea, won't compile). > >> > >> I agree. In fact I mistyped the functions names on my previous > >> email.... I really meant tcg2_measurement_init(). The patchset I > >> pointed you to already converts tcg2_log_prepare_buffer() to static. > > > > Replying to myself here, but.. In order to do that you do need the > > unification patches. tcg2_measurement_init() will need to allocate the > > appropriate buffer depending on EFI or not. > > So this is how it would look like with your patches on top: > https://github.com/u-boot/u-boot/compare/master...lnussel:u-boot:tpm-with-ilias-patches > > IMO the untangle patch is not needed. Does that look sensible?
You can skip the untangle patch the way you've changed efi_tcg2.c, that's fine. However, there's a few issues I tested for - A u32 err; that's not needed in EFI anymore - tcg2_measurement_init() calls tcg2_log_prepare_buffer, with NULL. I suspect you meant to call with elog, since the EFI booting is now broken and the kernel complains about an incomplete EventLog ([Firmware Bug]: Failed to parse event in TPM Final Events Log). But since we've gone through that effort, wouldn't it make more sense to have tcg2_measurement_init() set the priv->log if the pointer is valid and provided? /Ilias > > cu > Ludwig > > -- > Ludwig Nussel > Siemens AG > www.siemens.com
