Hi François, On Mon, 1 Nov 2021 at 02:53, François Ozog <francois.o...@linaro.org> wrote: > > Hi Simon, > > this seems a great endeavor. I'd like to better understand the scope of it. > > Is it to be used as part of what could become a U-Boot entry ABI scheme? By > that I mean giving some fixed aspects > to U-Boot entry while letting boards to have flexibility (say for instance > that the first 5 architecture ABI > parameter registers are reserved for U-Boot), and the Passage is about > specifying either those reserved registers > or one of them?
The goal is to provide a standard entry scheme for all firmware binaries. Whether it achieves that (or can with some mods) is up for discussion. Re the registers, do you think we need 5? > > Thinking entry ABI, here is what I observed on Arm: > > Linux has two entry ABIs: > - plain: x0 = dtb; > command line = dtb:/chosen/bootargs; initrd = > dtb:/chosen/linux,initrd-* > - EFI: x0=handle, x1=systemtable, x30=return address; > dtb = EFI_UUID config table; initrd = efi:<loadfile2(INITRD vendor > media UUID); command line = efi: image_protocol::load_options > > U-Boot (proper) has plenty of schemes: > - dtb is passed as either x0, x1, fixed memory area (Qemu which is bad in > itself), or other registers > - additional information passing: board specific register scheme, SMC calls > - U-Boot for RPI boards implement a Linux shaped entry ABI to be launched by > Videocore firmware > > Based on all the above, I would tend to think that RPI scheme is a good idea > but also > shall not prevent additional schemes for the boards. I was not actually considering Linux since I believe/assume its entry scheme is fixed and not up for discussion. I also did not think about the EFI case. As I understand it we cannot touch it as it is used by UEFI today. Maybe it is even in the standard? Really I am hoping we can start afresh...? > > What about a U-Boot Arm entry ABI like: > - plain: x0=dtb, x1=<Passage defined>, x2-x5 = <reserved>, other registers > are per platform, SMC calls allowed too Hmm we don't actually need the dtb as it is available in the bloblist. But I added an offset to it as a convenience. > - EFI: x0=handle, x1=systemtable, x30=return address; (when U-Boot is > launched as an EFI app) > dtb = EFI_UUID config table, + Passage = Passage UUID config table I don't understand the last line. Where is the passage info / bloblist? Do you mean it goes in the HOB list with a UUID? I suppose that is the most EFI-compatible way. What do you think about the idea of using an offset into the bloblist for the dtb? Also, can we make the standard passage ABI a build-time option, so it is deterministic? > > We could further leverage Passage to pass Operating Systems parameters that > could be removed from device tree (migration of /chosen to Passage). Memory > inventory would still be in DT but allocations for CMA or GPUs would be in > Passage. This idea is to reach a point where device tree is a "pristine" > hardware description. I'm worried about this becoming a substitute for devicetree. Really my intent is to provide a way to pass simple info, whereas what you talk about there seems like something that should be DT, just that it might need suitable bindings. As you know I have more expansive views about what should be in DT. > > Cheers > > PS: as Ilias mentions, this patch set contains bug fixes, non immediately > related additional functions (DM stats). It would be great to carve those out > to fast path them and keep this one with the very core of your idea. The DM stats is used in 'passage: Report the devicetree source'. I know it is sideways but I think it is better to make the output line more useful than just reporting the devicetree source. The first patch is indeed unrelated. I will pick it up so we can drop it for the next rev. Regards, Simon > > On Mon, 1 Nov 2021 at 02:17, Simon Glass <s...@chromium.org> wrote: >> >> >> This series adds a standard way of passing information between different >> firmware phases. This already exists in U-Boot at a very basic level, in >> the form of a bloblist containing an spl_handoff structure, but the intent >> here is to define something useful across projects. >> >> The need for this is growing as firmware fragments into multiple binaries >> each with its own purpose. Without any run-time connection, we must rely >> on build-time settings which are brittle and painful to keep in sync. >> >> This feature is named 'standard passage' since the name is more unique >> than many others that could be chosen, it is a passage in the sense that >> information is flowing from one place to another and it is standard, >> because that is what we want to create. >> >> The implementation is simply a pointer to a bloblist in a register, with >> an extra register to point to a devicetree, for more complex data, if one >> is present in the bloblist. This should cover all cases (small memory >> footprint as well as complex data flow) and be easy enough to implement on >> all architectures. >> >> The core bloblist code is relicensed to BSD-3-Clause in case it is useful >> in non-GPL projects but there is no requirement to use the same code. >> >> This series includes tweaks to the bloblist implementation in U-Boot to >> make it more suitable for the task, including: >> >> - Allocate tags explicitly in the enum >> - Put the magic number first >> - Define a process for adding tags >> >> The emphasis is on enabling open communcation between binaries, not >> enabling passage of secret, undocumented data, although this is possible >> in a private environment. >> >> This series is built on the OF_BOARD series It is available at >> u-boot-dm/pass-working or: >> >> https://source.denx.de/u-boot/custodians/u-boot-dm/-/commit/073b5c156f222c69a98b8ebcaa563d1ff10eb217 >> >> >> Simon Glass (31): >> Makefile: Correct TPL rule for OF_REAL >> kconfig: Add support for conditional values >> dm: core: Allow getting some basic stats >> stddef: Avoid warning with clang with offsetof() >> fdt: Drop SPL_BUILD macro >> bloblist: Put the magic number first >> bloblist: Rename the SPL tag >> bloblist: Drop unused tags >> bloblist: Use explicit numbering for the tags >> bloblist: Support allocating the bloblist >> bloblist: Use LOG_CATEGORY to simply logging >> bloblist: Use 'phase' consistently for bloblists >> bloblist: Refactor Kconfig to support alloc or fixed >> arm: qemu: Add an SPL build >> bloblist: Add functions to obtain base address and size >> passage: Support an incoming passage >> passage: Support a control devicetree >> passage: arm: Accept a passage from the previous phase >> passage: spl: Support adding the dtb to the passage bloblist >> passage: spl: Support passing the passage to U-Boot >> passage: Record where the devicetree came from >> passage: Report the devicetree source >> passage: Add a qemu test for ARM >> bloblist: doc: Bring in the API documentation >> bloblist: Relicense to allow BSD-3-Clause >> sandbox: Add a way of checking structs for standard passage >> passage: Add documentation >> passage: Add docs for spl_handoff >> x86: Move Intel GNVS file into the common include directory >> passage: Add checks for pre-existing blobs >> WIP: RFC: Add a gitlab test >> >> .gitlab-ci.yml | 6 + >> MAINTAINERS | 10 + >> Makefile | 2 +- >> arch/arm/cpu/armv7/start.S | 7 +- >> arch/arm/dts/qemu-arm-u-boot.dtsi | 22 ++ >> arch/arm/lib/crt0.S | 4 + >> arch/arm/mach-qemu/Kconfig | 9 + >> arch/sandbox/cpu/spl.c | 2 +- >> arch/x86/cpu/apollolake/acpi.c | 2 +- >> arch/x86/cpu/broadwell/cpu_from_spl.c | 4 +- >> arch/x86/cpu/intel_common/acpi.c | 2 +- >> .../include/asm/arch-apollolake/global_nvs.h | 2 +- >> arch/x86/lib/spl.c | 2 +- >> arch/x86/lib/tpl.c | 2 +- >> board/emulation/qemu-arm/Kconfig | 23 +- >> board/emulation/qemu-arm/MAINTAINERS | 1 + >> board/emulation/qemu-arm/Makefile | 1 + >> board/emulation/qemu-arm/spl.c | 27 ++ >> board/google/chromebook_coral/coral.c | 2 +- >> board/sandbox/Makefile | 3 +- >> board/sandbox/stdpass_check.c | 107 ++++++ >> cmd/bdinfo.c | 2 + >> common/Kconfig | 161 ++++++++- >> common/bloblist.c | 124 +++++-- >> common/board_f.c | 48 ++- >> common/board_r.c | 18 + >> common/spl/spl.c | 74 +++- >> configs/qemu_arm_spl_defconfig | 78 +++++ >> doc/board/emulation/qemu-arm.rst | 38 +++ >> doc/develop/bloblist.rst | 28 +- >> doc/develop/index.rst | 1 + >> doc/develop/std_passage.rst | 319 ++++++++++++++++++ >> drivers/core/device.c | 11 + >> drivers/core/root.c | 7 + >> drivers/core/uclass.c | 13 + >> drivers/serial/serial-uclass.c | 3 +- >> dts/Kconfig | 12 + >> include/asm-generic/global_data.h | 35 ++ >> include/bloblist.h | 175 +++++++--- >> include/dm/device.h | 11 +- >> include/dm/root.h | 8 + >> include/dm/uclass-internal.h | 7 + >> include/fdtdec.h | 40 ++- >> include/handoff.h | 8 +- >> .../x86/include/asm => include}/intel_gnvs.h | 0 >> include/linux/kconfig.h | 18 + >> include/linux/stddef.h | 8 +- >> include/spl.h | 15 + >> include/stdpass/README | 4 + >> include/stdpass/tpm2_eventlog.h | 42 +++ >> include/stdpass/vboot_ctx.h | 267 +++++++++++++++ >> lib/asm-offsets.c | 5 + >> lib/fdtdec.c | 65 +++- >> scripts/config_whitelist.txt | 1 + >> test/bloblist.c | 21 +- >> test/dm/core.c | 41 +++ >> test/py/tests/test_passage.py | 11 + >> 57 files changed, 1798 insertions(+), 161 deletions(-) >> create mode 100644 arch/arm/dts/qemu-arm-u-boot.dtsi >> create mode 100644 board/emulation/qemu-arm/spl.c >> create mode 100644 board/sandbox/stdpass_check.c >> create mode 100644 configs/qemu_arm_spl_defconfig >> create mode 100644 doc/develop/std_passage.rst >> rename {arch/x86/include/asm => include}/intel_gnvs.h (100%) >> create mode 100644 include/stdpass/README >> create mode 100644 include/stdpass/tpm2_eventlog.h >> create mode 100644 include/stdpass/vboot_ctx.h >> create mode 100644 test/py/tests/test_passage.py >> >> -- >> 2.33.1.1089.g2158813163f-goog >> > > > -- > François-Frédéric Ozog | Director Business Development > T: +33.67221.6485 > francois.o...@linaro.org | Skype: ffozog >
