[PATCH v2 00/15] qcom: smem: modernize SMEM in U-Boot
Casey Connolly
casey.connolly at linaro.org
Tue May 5 14:25:01 CEST 2026
On 05/05/2026 12:11, Sumit Garg wrote:
> Hi Casey,
>
> Thanks for the much needed re-spin of the SMEM patch-set.
>
> On Mon, May 04, 2026 at 08:57:28PM +0200, Casey Connolly wrote:
>> Smem is currently implemented a uclass in U-Boot. This carries with it
>> some implicit limitations about how and when we can actually talk with
>> it, since its modelled as a device.
>>
>> The SMEM uclass is qualcomm specific and has no other users, smem is
>> also largely useful for parsing the memory map and other tasks which we
>> have to do before DM is alive anyway.
>>
>> Let's drop the old smem code and replace it with a straight port from
>> Linux, providing a familiar interface and enabling us to access it much
>> earlier in the boot process than would be possible with a standard
>> udevice.
>>
>> Additionally, this will be easier to maintain going forwards since any
>> patches from Linux can be more easily ported over.
>>
>> With this new smem framework in place, we can now use SMEM to parse the
>> memory map when it's not provided via some other mechanism and to read
>> the serial number of the board.
>>
>> Implement this functionality and split the snapdragon memory parsing off
>> to its own file to try and organise things a bit better.
>>
>> Since the memory map stored in SMEM doesn't already have some carveouts
>> let's also be correct about unmapping reserved memory regions, we
>> should eventually do this on all Qualcomm boards but it's particularly
>> important when we aren't chainloading from ABL.
>
> This was really needed to unmap reserved regions in U-Boot memory map to
> increase robustness.
agreed, the ~100ms cost sucks but I hope we can bring it down by doing
this after dcache enable if we can figure that out (would probably rely
on starting with an initial minimal map to avoid the prefetcher issues)
but yeah, a problem for the future for sure.
>
>>
>> This depends on a fix for unmapping memory regions: https://lore.kernel.org/u-boot/20260504175511.585797-1-casey.connolly@linaro.org/
>>
>> ---
>> Changes in v2:
>> - Ensure reserved regions are unmapped appropriately when using SMEM as
>> the source of truth for the memory map.
>> - Support SMEM ram layout v0/v1 for older platforms using a header from
>> Qualcomm.
>
> It would be better if you can provide proper attribution in the commit
> to which this header is being picked up.
Where is the header sourced from? I can't really use another patch
posting as a source.
>
>> - Set an environment variable (memmap_source) providing info about
>> where U-Boots memory map is from.
>> - Correctly handle serial_num missing on msm8916
>> - Link to v1: https://lore.kernel.org/r/20241124-b4-modernise-smem-v1-0-b7852c11b67c@linaro.org
>>
>
> FWIW, I tested this patch-set on RB3Gen2 and lemans-evk after dropping
> the U-Boot DT overrides, so feel free to carry:
Good to know! I assume you removed the hardcoded DT memorymap for testing?
>
> Tested-by: Sumit Garg <sumit.garg at oss.qualcomm.com>
>
> I will give a proper review to this series soon.
Thanks
>
> -Sumit
>
>> To: u-boot at lists.denx.de
>> To: Sumit Garg <sumit.garg at kernel.org>
>> To: u-boot-qcom at groups.io
>> Cc: Tom Rini <trini at konsulko.com>
>> Cc: Simon Glass <sjg at chromium.org>
>> Cc: Casey Connolly <casey.connolly at linaro.org>
>> Cc: Peng Fan <peng.fan at nxp.com>
>> Cc: Marek Vasut <marek.vasut+renesas at mailbox.org>
>> Cc: Alice Guo <alice.guo at nxp.com>
>> Cc: Quentin Schulz <quentin.schulz at cherry.de>
>> Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
>> Cc: Neil Armstrong <neil.armstrong at linaro.org>
>> Cc: Mattijs Korpershoek <mkorpershoek at kernel.org>
>> Cc: Kuan-Wei Chiu <visitorckw at gmail.com>
>> Cc: Raymond Mao <raymond.mao at riscstar.com>
>> Cc: Stefan Roese <stefan.roese at mailbox.org>
>> Cc: Philip Molloy <philip.molloy at analog.com>
>> Cc: Jerome Forissier <jerome.forissier at arm.com>
>> Cc: Marek Vasut <marek.vasut at mailbox.org>
>> Cc: Varadarajan Narayanan <varadarajan.narayanan at oss.qualcomm.com>
>> Cc: Patrice Chotard <patrice.chotard at foss.st.com>
>> Cc: Aswin Murugan <aswin.murugan at oss.qualcomm.com>
>> Cc: Rasmus Villemoes <ravi at prevas.dk>
>> Cc: Heiko Schocher <hs at nabladev.com>
>> Cc: Michal Simek <michal.simek at amd.com>
>> Cc: Sughosh Ganu <sughosh.ganu at arm.com>
>> Cc: Antony Kurniawan Soemardi <linux at smankusors.com>
>> Cc: Luca Weiss <luca.weiss at fairphone.com>
>> Cc: Balaji Selvanathan <balaji.selvanathan at oss.qualcomm.com>
>>
>> ---
>> Casey Connolly (15):
>> Revert "dm: SMEM (Shared memory) uclass"
>> smem: drop drivers/smem
>> Revert "test: smem: add basic smem test"
>> Revert "drivers: smem: sandbox"
>> mach-snapdragon: fix reserved memory carveout
>> soc: qcom: import smem from Linux 6.11-rc2
>> soc: qcom: smem: adjust headers for U-Boot
>> soc: qcom: smem: adjust for U-Boot
>> soc: qcom: smem: get serial number from socinfo
>> soc: qcom: smem: stub functions
>> soc: qcom: smem: add build infra
>> mach-snapdragon: move memory parsing to its own file
>> mach-snapdragon: support parsing memory map from SMEM
>> mach-snapdragon: fetch serial# from SMEM
>> configs: add qcom_sm8650_defconfig and debug fragment
>>
>> MAINTAINERS | 1 -
>> arch/arm/Kconfig | 3 +-
>> arch/arm/mach-snapdragon/Makefile | 2 +-
>> arch/arm/mach-snapdragon/board.c | 253 ++++-----
>> arch/arm/mach-snapdragon/dram.c | 239 ++++++++
>> arch/arm/mach-snapdragon/qcom-priv.h | 17 +
>> arch/arm/mach-snapdragon/rampart.h | 194 +++++++
>> arch/sandbox/dts/test.dts | 4 -
>> board/qualcomm/debug-sm8650.config | 5 +
>> configs/qcom_sm8650_defconfig | 16 +
>> configs/sandbox64_defconfig | 2 -
>> configs/sandbox_defconfig | 2 -
>> drivers/Kconfig | 2 -
>> drivers/Makefile | 1 -
>> drivers/smem/Kconfig | 25 -
>> drivers/smem/Makefile | 7 -
>> drivers/smem/sandbox_smem.c | 44 --
>> drivers/smem/smem-uclass.c | 46 --
>> drivers/soc/qcom/Kconfig | 8 +
>> drivers/soc/qcom/Makefile | 1 +
>> drivers/{smem/msm_smem.c => soc/qcom/smem.c} | 777 ++++++++++++++++-----------
>> include/dm/uclass-id.h | 1 -
>> include/smem.h | 90 ----
>> include/soc/qcom/smem.h | 36 ++
>> include/soc/qcom/socinfo.h | 111 ++++
>> test/dm/Makefile | 1 -
>> test/dm/smem.c | 26 -
>> 27 files changed, 1186 insertions(+), 728 deletions(-)
>> ---
>> base-commit: 2920b49fb117dd70b6219804bf0d298c96f184f2
>>
>> // Casey (she/they)
>>
--
// Casey (she/her)
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