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Message-ID: <20251126160854.553077-9-tzimmermann@suse.de>
Date: Wed, 26 Nov 2025 17:03:25 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: ardb@...nel.org,
javierm@...hat.com,
arnd@...db.de,
richard.lyu@...e.com,
helgaas@...nel.org
Cc: x86@...nel.org,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
linux-efi@...r.kernel.org,
loongarch@...ts.linux.dev,
linux-riscv@...ts.infradead.org,
dri-devel@...ts.freedesktop.org,
linux-hyperv@...r.kernel.org,
linux-pci@...r.kernel.org,
linux-fbdev@...r.kernel.org,
Thomas Zimmermann <tzimmermann@...e.de>
Subject: [PATCH v3 8/9] efi: Support EDID information
In the EFI config table, rename LINUX_EFI_SCREEN_INFO_TABLE_GUID to
LINUX_EFI_PRIMARY_DISPLAY_TABLE_GUID. Read sysfb_primary_display
from the entry. In addition to the screen_info, the entry now also
contains EDID information.
In libstub, replace struct screen_info with struct sysfb_display_info
from the kernel's sysfb_primary_display and rename functions accordingly.
Transfer it to the runtime kernel using the kernel's global state or
the config-table entry LINUX_EFI_PRIMARY_DISPLAY_TABLE_GUID.
With CONFIG_FIRMWARE_EDID=y, libstub now transfers the GOP device's
EDID information to the kernel. If CONFIG_FIRMWARE_EDID=n, EDID
information is disabled. Make the Kconfig symbol CONFIG_FIRMWARE_EDID
available with EFI. Setting the value to 'n' disables EDID support.
Also rename screen_info.c to primary_display.c and adapt the contained
comment according to the changes.
v3:
- replace SCREEN_INFO table (Ard)
- merge libstub changes
Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
---
arch/loongarch/kernel/efi.c | 17 +++---
drivers/firmware/efi/efi-init.c | 17 +++---
drivers/firmware/efi/efi.c | 4 +-
drivers/firmware/efi/libstub/Makefile | 2 +-
drivers/firmware/efi/libstub/efi-stub-entry.c | 11 ++--
drivers/firmware/efi/libstub/efi-stub.c | 41 +++++++++-----
drivers/firmware/efi/libstub/efistub.h | 7 ++-
.../firmware/efi/libstub/primary_display.c | 56 +++++++++++++++++++
drivers/firmware/efi/libstub/screen_info.c | 53 ------------------
drivers/firmware/efi/libstub/zboot.c | 4 +-
drivers/video/Kconfig | 8 ++-
include/linux/efi.h | 9 +--
12 files changed, 123 insertions(+), 106 deletions(-)
create mode 100644 drivers/firmware/efi/libstub/primary_display.c
delete mode 100644 drivers/firmware/efi/libstub/screen_info.c
diff --git a/arch/loongarch/kernel/efi.c b/arch/loongarch/kernel/efi.c
index 1ef38036e8ae..342aca00d42c 100644
--- a/arch/loongarch/kernel/efi.c
+++ b/arch/loongarch/kernel/efi.c
@@ -72,7 +72,7 @@ bool efi_poweroff_required(void)
(acpi_gbl_reduced_hardware || acpi_no_s5);
}
-unsigned long __initdata screen_info_table = EFI_INVALID_TABLE_ADDR;
+unsigned long __initdata primary_display_table = EFI_INVALID_TABLE_ADDR;
#if defined(CONFIG_SYSFB) || defined(CONFIG_EFI_EARLYCON)
struct sysfb_display_info sysfb_primary_display __section(".data");
@@ -81,16 +81,17 @@ EXPORT_SYMBOL_GPL(sysfb_primary_display);
static void __init init_primary_display(void)
{
- if (screen_info_table == EFI_INVALID_TABLE_ADDR) {
- struct screen_info *si = early_memremap(screen_info_table, sizeof(*si));
+ if (primary_display_table != EFI_INVALID_TABLE_ADDR) {
+ struct sysfb_display_info *dpy =
+ early_memremap(primary_display_table, sizeof(*dpy));
- if (!si) {
- pr_err("Could not map screen_info config table\n");
+ if (!dpy) {
+ pr_err("Could not map primary_display config table\n");
return;
}
- sysfb_primary_display.screen = *si;
- memset(si, 0, sizeof(*si));
- early_memunmap(si, sizeof(*si));
+ sysfb_primary_display = *dpy;
+ memset(dpy, 0, sizeof(*dpy));
+ early_memunmap(dpy, sizeof(*dpy));
} else {
return;
}
diff --git a/drivers/firmware/efi/efi-init.c b/drivers/firmware/efi/efi-init.c
index ca697d485116..b22e208a1aae 100644
--- a/drivers/firmware/efi/efi-init.c
+++ b/drivers/firmware/efi/efi-init.c
@@ -23,7 +23,7 @@
#include <asm/efi.h>
-unsigned long __initdata screen_info_table = EFI_INVALID_TABLE_ADDR;
+unsigned long __initdata primary_display_table = EFI_INVALID_TABLE_ADDR;
static int __init is_memory(efi_memory_desc_t *md)
{
@@ -67,16 +67,17 @@ EXPORT_SYMBOL_GPL(sysfb_primary_display);
static void __init init_primary_display(void)
{
- if (screen_info_table != EFI_INVALID_TABLE_ADDR) {
- struct screen_info *si = early_memremap(screen_info_table, sizeof(*si));
+ if (primary_display_table != EFI_INVALID_TABLE_ADDR) {
+ struct sysfb_display_info *dpy =
+ early_memremap(primary_display_table, sizeof(*dpy));
- if (!si) {
- pr_err("Could not map screen_info config table\n");
+ if (!dpy) {
+ pr_err("Could not map primary_display config table\n");
return;
}
- sysfb_primary_display.screen = *si;
- memset(si, 0, sizeof(*si));
- early_memunmap(si, sizeof(*si));
+ sysfb_primary_display = *dpy;
+ memset(dpy, 0, sizeof(*dpy));
+ early_memunmap(dpy, sizeof(*dpy));
} else {
return;
}
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index a9070d00b833..955193691f10 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -63,7 +63,7 @@ static unsigned long __initdata mem_reserve = EFI_INVALID_TABLE_ADDR;
static unsigned long __initdata rt_prop = EFI_INVALID_TABLE_ADDR;
static unsigned long __initdata initrd = EFI_INVALID_TABLE_ADDR;
-extern unsigned long screen_info_table;
+extern unsigned long primary_display_table;
struct mm_struct efi_mm = {
.mm_mt = MTREE_INIT_EXT(mm_mt, MM_MT_FLAGS, efi_mm.mmap_lock),
@@ -641,7 +641,7 @@ static const efi_config_table_type_t common_tables[] __initconst = {
{LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID, &efi.unaccepted, "Unaccepted" },
#endif
#ifdef CONFIG_EFI_GENERIC_STUB
- {LINUX_EFI_SCREEN_INFO_TABLE_GUID, &screen_info_table },
+ {LINUX_EFI_PRIMARY_DISPLAY_TABLE_GUID, &primary_display_table },
#endif
{},
};
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 7d15a85d579f..e386ffd009b7 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -80,7 +80,7 @@ $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
$(call if_changed_rule,cc_o_c)
lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o string.o intrinsics.o systable.o \
- screen_info.o efi-stub-entry.o
+ primary_display.o efi-stub-entry.o
lib-$(CONFIG_ARM) += arm32-stub.o
lib-$(CONFIG_ARM64) += kaslr.o arm64.o arm64-stub.o smbios.o
diff --git a/drivers/firmware/efi/libstub/efi-stub-entry.c b/drivers/firmware/efi/libstub/efi-stub-entry.c
index 401ecbbdf331..aa85e910fe59 100644
--- a/drivers/firmware/efi/libstub/efi-stub-entry.c
+++ b/drivers/firmware/efi/libstub/efi-stub-entry.c
@@ -14,18 +14,15 @@ static void *kernel_image_addr(void *addr)
return addr + kernel_image_offset;
}
-struct screen_info *alloc_screen_info(void)
+struct sysfb_display_info *alloc_primary_display(void)
{
if (IS_ENABLED(CONFIG_ARM))
- return __alloc_screen_info();
+ return __alloc_primary_display();
if (IS_ENABLED(CONFIG_X86) ||
IS_ENABLED(CONFIG_EFI_EARLYCON) ||
- IS_ENABLED(CONFIG_SYSFB)) {
- struct sysfb_display_info *dpy = kernel_image_addr(&sysfb_primary_display);
-
- return &dpy->screen;
- }
+ IS_ENABLED(CONFIG_SYSFB))
+ return kernel_image_addr(&sysfb_primary_display);
return NULL;
}
diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
index 9cb814c5ba1b..42d6073bcd06 100644
--- a/drivers/firmware/efi/libstub/efi-stub.c
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -10,7 +10,7 @@
*/
#include <linux/efi.h>
-#include <linux/screen_info.h>
+#include <linux/sysfb.h>
#include <asm/efi.h>
#include "efistub.h"
@@ -48,23 +48,33 @@
static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);
-void __weak free_screen_info(struct screen_info *si)
-{
-}
+void __weak free_primary_display(struct sysfb_display_info *dpy)
+{ }
-static struct screen_info *setup_graphics(void)
+static struct sysfb_display_info *setup_primary_display(void)
{
- struct screen_info *si, tmp = {};
+ struct sysfb_display_info *dpy;
+ struct screen_info *screen = NULL;
+ struct edid_info *edid = NULL;
+ efi_status_t status;
- if (efi_setup_graphics(&tmp, NULL) != EFI_SUCCESS)
+ dpy = alloc_primary_display();
+ if (!dpy)
return NULL;
+ screen = &dpy->screen;
+#if defined(CONFIG_FIRMWARE_EDID)
+ edid = &dpy->edid;
+#endif
- si = alloc_screen_info();
- if (!si)
- return NULL;
+ status = efi_setup_graphics(screen, edid);
+ if (status != EFI_SUCCESS)
+ goto err_free_primary_display;
- *si = tmp;
- return si;
+ return dpy;
+
+err_free_primary_display:
+ free_primary_display(dpy);
+ return NULL;
}
static void install_memreserve_table(void)
@@ -145,14 +155,14 @@ efi_status_t efi_stub_common(efi_handle_t handle,
unsigned long image_addr,
char *cmdline_ptr)
{
- struct screen_info *si;
+ struct sysfb_display_info *dpy;
efi_status_t status;
status = check_platform_features();
if (status != EFI_SUCCESS)
return status;
- si = setup_graphics();
+ dpy = setup_primary_display();
efi_retrieve_eventlog();
@@ -172,7 +182,8 @@ efi_status_t efi_stub_common(efi_handle_t handle,
status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
- free_screen_info(si);
+ free_primary_display(dpy);
+
return status;
}
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index b2fb0c3fa721..979a21818cc1 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -36,6 +36,7 @@
struct edid_info;
struct screen_info;
+struct sysfb_display_info;
extern bool efi_no5lvl;
extern bool efi_nochunk;
@@ -1175,9 +1176,9 @@ efi_enable_reset_attack_mitigation(void) { }
void efi_retrieve_eventlog(void);
-struct screen_info *alloc_screen_info(void);
-struct screen_info *__alloc_screen_info(void);
-void free_screen_info(struct screen_info *si);
+struct sysfb_display_info *alloc_primary_display(void);
+struct sysfb_display_info *__alloc_primary_display(void);
+void free_primary_display(struct sysfb_display_info *dpy);
void efi_cache_sync_image(unsigned long image_base,
unsigned long alloc_size);
diff --git a/drivers/firmware/efi/libstub/primary_display.c b/drivers/firmware/efi/libstub/primary_display.c
new file mode 100644
index 000000000000..cdaebab26514
--- /dev/null
+++ b/drivers/firmware/efi/libstub/primary_display.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/efi.h>
+#include <linux/sysfb.h>
+
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+/*
+ * There are two ways of populating the core kernel's sysfb_primary_display
+ * via the stub:
+ *
+ * - using a configuration table, which relies on the EFI init code to
+ * locate the table and copy the contents; or
+ *
+ * - by linking directly to the core kernel's copy of the global symbol.
+ *
+ * The latter is preferred because it makes the EFIFB earlycon available very
+ * early, but it only works if the EFI stub is part of the core kernel image
+ * itself. The zboot decompressor can only use the configuration table
+ * approach.
+ */
+
+static efi_guid_t primary_display_guid = LINUX_EFI_PRIMARY_DISPLAY_TABLE_GUID;
+
+struct sysfb_display_info *__alloc_primary_display(void)
+{
+ struct sysfb_display_info *dpy;
+ efi_status_t status;
+
+ status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY,
+ sizeof(*dpy), (void **)&dpy);
+
+ if (status != EFI_SUCCESS)
+ return NULL;
+
+ memset(dpy, 0, sizeof(*dpy));
+
+ status = efi_bs_call(install_configuration_table,
+ &primary_display_guid, dpy);
+ if (status == EFI_SUCCESS)
+ return dpy;
+
+ efi_bs_call(free_pool, dpy);
+ return NULL;
+}
+
+void free_primary_display(struct sysfb_display_info *dpy)
+{
+ if (!dpy)
+ return;
+
+ efi_bs_call(install_configuration_table, &primary_display_guid, NULL);
+ efi_bs_call(free_pool, dpy);
+}
diff --git a/drivers/firmware/efi/libstub/screen_info.c b/drivers/firmware/efi/libstub/screen_info.c
deleted file mode 100644
index 5d3a1e32d177..000000000000
--- a/drivers/firmware/efi/libstub/screen_info.c
+++ /dev/null
@@ -1,53 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-#include <linux/efi.h>
-#include <linux/screen_info.h>
-
-#include <asm/efi.h>
-
-#include "efistub.h"
-
-/*
- * There are two ways of populating the core kernel's struct screen_info via the stub:
- * - using a configuration table, like below, which relies on the EFI init code
- * to locate the table and copy the contents;
- * - by linking directly to the core kernel's copy of the global symbol.
- *
- * The latter is preferred because it makes the EFIFB earlycon available very
- * early, but it only works if the EFI stub is part of the core kernel image
- * itself. The zboot decompressor can only use the configuration table
- * approach.
- */
-
-static efi_guid_t screen_info_guid = LINUX_EFI_SCREEN_INFO_TABLE_GUID;
-
-struct screen_info *__alloc_screen_info(void)
-{
- struct screen_info *si;
- efi_status_t status;
-
- status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY,
- sizeof(*si), (void **)&si);
-
- if (status != EFI_SUCCESS)
- return NULL;
-
- memset(si, 0, sizeof(*si));
-
- status = efi_bs_call(install_configuration_table,
- &screen_info_guid, si);
- if (status == EFI_SUCCESS)
- return si;
-
- efi_bs_call(free_pool, si);
- return NULL;
-}
-
-void free_screen_info(struct screen_info *si)
-{
- if (!si)
- return;
-
- efi_bs_call(install_configuration_table, &screen_info_guid, NULL);
- efi_bs_call(free_pool, si);
-}
diff --git a/drivers/firmware/efi/libstub/zboot.c b/drivers/firmware/efi/libstub/zboot.c
index c47ace06f010..4b76f74c56da 100644
--- a/drivers/firmware/efi/libstub/zboot.c
+++ b/drivers/firmware/efi/libstub/zboot.c
@@ -26,9 +26,9 @@ void __weak efi_cache_sync_image(unsigned long image_base,
// executable code loaded into memory to be safe for execution.
}
-struct screen_info *alloc_screen_info(void)
+struct sysfb_display_info *alloc_primary_display(void)
{
- return __alloc_screen_info();
+ return __alloc_primary_display();
}
asmlinkage efi_status_t __efiapi
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index d51777df12d1..f452fac90a9f 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -63,11 +63,13 @@ endif # HAS_IOMEM
config FIRMWARE_EDID
bool "Enable firmware EDID"
- depends on X86
+ depends on EFI || X86
help
This enables access to the EDID transferred from the firmware.
- On x86, this is from the VESA BIOS. DRM display drivers will
- be able to export the information to userspace.
+ On EFI systems, the EDID comes from the same device as the
+ primary GOP. On x86 with BIOS, it comes from the VESA BIOS.
+ DRM display drivers will be able to export the information
+ to userspace.
Also enable this if DDC/I2C transfers do not work for your driver
and if you are using nvidiafb, i810fb or savagefb.
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 2a43094e23f7..664898d09ff5 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -406,11 +406,12 @@ void efi_native_runtime_setup(void);
#define EFI_CC_FINAL_EVENTS_TABLE_GUID EFI_GUID(0xdd4a4648, 0x2de7, 0x4665, 0x96, 0x4d, 0x21, 0xd9, 0xef, 0x5f, 0xb4, 0x46)
/*
- * This GUID is used to pass to the kernel proper the struct screen_info
- * structure that was populated by the stub based on the GOP protocol instance
- * associated with ConOut
+ * This GUIDs are used to pass to the kernel proper the primary
+ * display that has been populated by the stub based on the GOP
+ * instance associated with ConOut.
*/
-#define LINUX_EFI_SCREEN_INFO_TABLE_GUID EFI_GUID(0xe03fc20a, 0x85dc, 0x406e, 0xb9, 0x0e, 0x4a, 0xb5, 0x02, 0x37, 0x1d, 0x95)
+#define LINUX_EFI_PRIMARY_DISPLAY_TABLE_GUID EFI_GUID(0xe03fc20a, 0x85dc, 0x406e, 0xb9, 0x0e, 0x4a, 0xb5, 0x02, 0x37, 0x1d, 0x95)
+
#define LINUX_EFI_ARM_CPU_STATE_TABLE_GUID EFI_GUID(0xef79e4aa, 0x3c3d, 0x4989, 0xb9, 0x02, 0x07, 0xa9, 0x43, 0xe5, 0x50, 0xd2)
#define LINUX_EFI_LOADER_ENTRY_GUID EFI_GUID(0x4a67b082, 0x0a4c, 0x41cf, 0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f)
#define LINUX_EFI_RANDOM_SEED_TABLE_GUID EFI_GUID(0x1ce1e5bc, 0x7ceb, 0x42f2, 0x81, 0xe5, 0x8a, 0xad, 0xf1, 0x80, 0xf5, 0x7b)
--
2.51.1
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