// SPDX-License-Identifier: GPL-2.0 #include <linux/efi.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. * * In order to support both methods from the same build of the EFI stub * library, provide this dummy global definition of struct screen_info. If it * is required to satisfy a link dependency, it means we need to override the * __weak alloc and free methods with the ones below, and those will be pulled * in as well. */ struct screen_info screen_info; 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; 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); }