Am 19. November 2025 19:46:40 MEZ schrieb Adriana Nicolae <[email protected]>: >From: adriana <[email protected]> > >The Linux kernel can discover SMBIOS tables through two primary methods: >1. Via EFI tables, when using EFI boot; >2. Via the 'smbios3-entrypoint' property in the /chosen node of the >device tree. > >When U-Boot boots a Linux kernel using a non-EFI command ("bootm", >"bootz", or "booti"), the kernel relies on the device tree to detect >the hardware. If SMBIOS tables are available in U-Boot, they should >be passed to the kernel via this device tree property. > >This patch modifies boot_fdt_prepare(), to inject the SMBIOSv3 table >address into the device tree if there is a table generated by U-boot. >The "board_fdt_chosen_smbios" is weak in order to leave the possibilty >for specific boards to select custom SMBIOS addresses. > >The changes in this patch are added in the context of supporting this >device tree property in linux kernel: >https://lkml.org/lkml/2025/10/24/1393 > >Device tree schema was updated to include the "smbios3-entrypoint" node >in pull request: https://github.com/devicetree-org/dt-schema/pull/177 > >Signed-off-by: Adriana Nicolae <[email protected]> >--- >Changes in v4: > - Remove weak function board_fdt_chosen_smbios(), replace with > gd_smbios_start(); > - Return -EAGAIN in test if GENERATE_SMBIOS_TABLE is not enabled; > - Remove unnecessary fdt cleanup at the end of the test; > - Added missing newlines at the end of the modified files. > >Changes in v3: > - Moved "board_fdt_chosen_smbios" function to lib/smbios.c > - Return physical address of smbios entry and use map_sysmem to > access the entry point; > - Removed check for config enabled and added check for > GENERATE_SMBIOS_TABLE; > - Add test to check that smbios entry address is added into fdt; > >Changes in v2: > - Renamed device tree property to "smbios3-entrypoint". > - Removed redundant check for CONFIG_SMBIOS. >--- > boot/fdt_support.c | 19 ++++++++++++++++++ > test/dm/fdtdec.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 67 insertions(+) > >diff --git a/boot/fdt_support.c b/boot/fdt_support.c >index 92f2f534ee0..1c215e548db 100644 >--- a/boot/fdt_support.c >+++ b/boot/fdt_support.c >@@ -27,6 +27,7 @@ > #include <fdtdec.h> > #include <version.h> > #include <video.h> >+#include <smbios.h> > > DECLARE_GLOBAL_DATA_PTR; > >@@ -333,6 +334,7 @@ int fdt_chosen(void *fdt) > int nodeoffset; > int err; > const char *str; /* used to set string properties */ >+ ulong smbiosaddr; /* SMBIOS table address */ > > err = fdt_check_header(fdt); > if (err < 0) { >@@ -387,6 +389,23 @@ int fdt_chosen(void *fdt) > return err; > } > >+ if (CONFIG_IS_ENABLED(GENERATE_SMBIOS_TABLE)) { >+ /* Inject SMBIOS address when we have a valid address. >+ * This is useful for systems using booti/bootm instead of >bootefi. >+ * Failure to set this property is non-fatal, we only generate a >+ * warning. >+ */ >+ smbiosaddr = gd_smbios_start(); >+ if (smbiosaddr) { >+ err = fdt_setprop_u64(fdt, nodeoffset, >"smbios3-entrypoint", >+ smbiosaddr); >+ if (err < 0) { >+ printf("WARNING: could not set >smbios3-entrypoint %s.\n", >+ fdt_strerror(err)); >+ } >+ } >+ } >+ > return fdt_fixup_stdout(fdt, nodeoffset); > } > >diff --git a/test/dm/fdtdec.c b/test/dm/fdtdec.c >index 1f24f1d5dff..1744211d4d1 100644 >--- a/test/dm/fdtdec.c >+++ b/test/dm/fdtdec.c >@@ -7,6 +7,9 @@ > #include <asm/global_data.h> > #include <dm/of_extra.h> > #include <dm/test.h> >+#include <fdt_support.h> >+#include <mapmem.h> >+#include <smbios.h> > #include <test/ut.h> > > DECLARE_GLOBAL_DATA_PTR; >@@ -129,3 +132,48 @@ static int dm_test_fdtdec_add_reserved_memory(struct >unit_test_state *uts) > } > DM_TEST(dm_test_fdtdec_add_reserved_memory, > UTF_SCAN_PDATA | UTF_SCAN_FDT | UTF_FLAT_TREE); >+ >+static int dm_test_fdt_chosen_smbios(struct unit_test_state *uts) >+{ >+ void *blob; >+ ulong val; >+ struct smbios3_entry *entry; >+ int chosen, blob_sz; >+ const fdt64_t *prop; >+ >+ if (!CONFIG_IS_ENABLED(GENERATE_SMBIOS_TABLE)) { >+ return -EAGAIN; >+ } >+ >+ blob_sz = fdt_totalsize(gd->fdt_blob) + 128;
This is very tight. Depending on the architecture more properties may be injected. 4 KiB is a safe value. >+ blob = malloc(blob_sz); Device-trees must be 8 byte aligned. Please, consider using memalign(blob_sz, 8). Best regards Heinrich >+ ut_assertnonnull(blob); >+ >+ /* Make a writable copy of the fdt blob */ >+ ut_assertok(fdt_open_into(gd->fdt_blob, blob, blob_sz)); >+ >+ /* Mock SMBIOS table */ >+ entry = map_sysmem(gd->arch.smbios_start, sizeof(struct smbios3_entry)); >+ memcpy(entry->anchor, "_SM3_", 5); >+ entry->length = sizeof(struct smbios3_entry); >+ unmap_sysmem(entry); >+ >+ /* Force fdt_chosen to run */ >+ ut_assertok(fdt_chosen(blob)); >+ >+ chosen = fdt_path_offset(blob, "/chosen"); >+ ut_assert(chosen >= 0); >+ >+ /* Verify the property exists */ >+ prop = fdt_getprop(blob, chosen, "smbios3-entrypoint", NULL); >+ ut_assertnonnull(prop); >+ >+ /* Verify the property matches smbios_start */ >+ val = fdt64_to_cpu(*prop); >+ ut_asserteq_64(gd->arch.smbios_start, val); >+ >+ free(blob); >+ >+ return 0; >+} >+DM_TEST(dm_test_fdt_chosen_smbios, UTF_SCAN_PDATA | UTF_SCAN_FDT);
