arch/x86: add support for Multiboot boot information structure
When booting using GRUB, some useful information about the environment is given to us via a boot information structure. We've not made any use of this information so far, but the x86 framebuffer driver will. A skeletal definition of the structure is given, and provisions are made to preserve its contents at boot if the configuration requires it. Signed-off-by: Charles E. Youse <charles.youse@intel.com>
This commit is contained in:
Charles E. Youse
Andrew Boie
parent
55ff4ba5df
commit
a1a3a4fced
7 changed files with 127 additions and 2 deletions
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@ -38,6 +38,7 @@
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/arch/x86/core/ @andrewboie
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/arch/x86/core/crt0.S @wentongwu @nashif
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/arch/x86/core/pcie.c @gnuless
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/arch/x86/core/multiboot.c @gnuless
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/soc/x86/ @andrewboie @wentongwu
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/soc/x86/intel_quark/quark_d2000/ @nashif
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/soc/x86/intel_quark/quark_se/ @nashif
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@ -206,6 +207,7 @@
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/include/arch/x86/ @andrewboie @wentongwu
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/include/arch/common/ @andrewboie @andyross @nashif
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/include/arch/x86/arch.h @andrewboie
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/include/arch/x86/multiboot.h @gnuless
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/include/arch/xtensa/ @andrewboie
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/include/atomic.h @andrewboie @andyross
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/include/bluetooth/ @joerchan @jhedberg @Vudentz
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@ -20,6 +20,15 @@ config X86_MULTIBOOT
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to leave this option on if you're not sure. It only expands the
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text segment by 12-16 bytes and is typically ignored if not needed.
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config X86_MULTIBOOT_INFO
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bool "Preserve multiboot information structure"
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depends on X86_MULTIBOOT
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default n
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help
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Multiboot passes a pointer to an information structure to the
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kernel entry point. Some drivers (e.g., the multiboot framebuffer
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display driver) need to refer to information in this structure,
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and so set this option to preserve the data in a permanent location.
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source "arch/x86/core/Kconfig"
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@ -35,6 +35,7 @@ zephyr_library_sources_if_kconfig( reboot_rst_cnt.c)
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zephyr_library_sources_if_kconfig( pcie.c)
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zephyr_library_sources_ifdef(CONFIG_LAZY_FP_SHARING float.c)
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zephyr_library_sources_ifdef(CONFIG_X86_USERSPACE userspace.S)
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zephyr_library_sources_ifdef(CONFIG_X86_MULTIBOOT multiboot.c)
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# Last since we declare default exception handlers here
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zephyr_library_sources(fatal.c)
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@ -14,6 +14,7 @@
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#include <arch/x86/asm.h>
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#include <kernel_arch_data.h>
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#include <arch/cpu.h>
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#include <arch/x86/multiboot.h>
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/* exports (private APIs) */
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@ -140,6 +141,28 @@ gdt_ptr:
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SECTION_FUNC(TEXT_START, __start)
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#ifdef CONFIG_X86_MULTIBOOT_INFO
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/*
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* If we were loaded by a multiboot-compliant loader, then EAX
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* contains X86_MULTIBOOT_EAX_MAGIC and EBX points to a 'struct
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* x86_multiboot_info' somewhere in memory that the kernel load
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* image doesn't claim. Since the kernel will consider such memory
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* "free", we must copy the contents of the struct before the kernel
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* decides to use that RAM for something else. However, we can't
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* effect the copy until after the BSS is initialized.
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*
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* EBX isn't touched until the copy is made; even function calls will
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* preserve it (it's callee-save in the SysV ABI). But EAX will be
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* clobbered, so we check for the magic now and leave a sentinel in
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* EBX (0) if the multiboot data isn't valid.
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*/
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cmpl $X86_MULTIBOOT_EAX_MAGIC, %eax
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je 1f
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xorl %ebx, %ebx
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1:
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#endif
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#ifdef CONFIG_BOOT_TIME_MEASUREMENT
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/*
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* Record BootTime from start of Kernel.
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@ -375,6 +398,23 @@ __csSet:
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#endif
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lidt z_x86_idt /* load 32-bit operand size IDT */
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#if defined(CONFIG_X86_MULTIBOOT_INFO)
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/*
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* If EBX isn't 0, then it points to a valid boot information
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* struct. Copy it to x86_multiboot_info before it's overwritten.
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*/
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testl %ebx, %ebx
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jz 1f
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movl $__X86_MULTIBOOT_INFO_SIZEOF, %ecx
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movl %ebx, %esi
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movl $x86_multiboot_info, %edi
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cld /* to be safe. should still be 0 from BSS clear, though */
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rep
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movsb
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1:
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#endif
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/* Jump to C portion of kernel initialization and never return */
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jmp z_cstart
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@ -477,7 +517,7 @@ z_x86_idt:
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.balign 4,0x90
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.long 0x1BADB002 /* multiboot magic number */
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.long X86_MULTIBOOT_HEADER_MAGIC
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/*
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* Flags = no bits are being set, specifically bit 16 is not being
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@ -494,7 +534,7 @@ z_x86_idt:
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* unsigned sum of zero.
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*/
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.long -(0x1BADB002 + 0)
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.long -(X86_MULTIBOOT_HEADER_MAGIC + 0)
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#endif /* CONFIG_X86_MULTIBOOT */
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#ifdef CONFIG_SET_GDT
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14
arch/x86/core/multiboot.c
Normal file
14
arch/x86/core/multiboot.c
Normal file
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@ -0,0 +1,14 @@
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/*
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* Copyright (c) 2019 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <kernel.h>
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#include <arch/x86/multiboot.h>
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#ifdef CONFIG_X86_MULTIBOOT_INFO
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struct x86_multiboot_info x86_multiboot_info;
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#endif /* CONFIG_X86_MULTIBOOT_INFO */
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@ -29,6 +29,7 @@
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#include <kernel_structs.h>
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#include <swapstk.h>
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#include <mmustructs.h>
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#include <arch/x86/multiboot.h>
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#include <kernel_offsets.h>
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@ -82,4 +83,9 @@ GEN_OFFSET_SYM(NANO_ESF, eflags);
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GEN_ABSOLUTE_SYM(__MMU_REGION_SIZEOF, sizeof(struct mmu_region));
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/* size of struct x86_multiboot_info, used by crt0.S */
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GEN_ABSOLUTE_SYM(__X86_MULTIBOOT_INFO_SIZEOF,
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sizeof(struct x86_multiboot_info));
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GEN_ABS_SYM_END
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53
include/arch/x86/multiboot.h
Normal file
53
include/arch/x86/multiboot.h
Normal file
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@ -0,0 +1,53 @@
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/*
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* Copyright (c) 2019 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef ZEPHYR_INCLUDE_ARCH_X86_MULTIBOOT_H_
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#define ZEPHYR_INCLUDE_ARCH_X86_MULTIBOOT_H_
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#ifndef _ASMLANGUAGE
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/*
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* Multiboot (version 1) boot information structure.
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*
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* Only fields/values of interest to Zephyr are enumerated: at
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* present, that means only those pertaining to the framebuffer.
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*/
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struct x86_multiboot_info {
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u32_t flags;
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u32_t unused0[21];
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u32_t fb_addr_lo;
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u32_t fb_addr_hi;
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u32_t fb_pitch;
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u32_t fb_width;
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u32_t fb_height;
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u8_t fb_bpp;
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u8_t fb_type;
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};
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extern struct x86_multiboot_info x86_multiboot_info;
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#endif /* _ASMLANGUAGE */
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/*
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* Magic numbers: the kernel multiboot header (see crt0.S) begins with
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* X86_MULTIBOOT_HEADER_MAGIC to signal to the booter that it supports
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* multiboot. On kernel entry, EAX is set to X86_MULTIBOOT_EAX_MAGIC to
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* signal that the boot loader is multiboot compliant.
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*/
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#define X86_MULTIBOOT_HEADER_MAGIC 0x1BADB002
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#define X86_MULTIBOOT_EAX_MAGIC 0x2BADB002
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/* The fb_* fields are valid if X86_MULTIBOOT_INFO_FLAGS_FB is set. */
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#define X86_MULTIBOOT_INFO_FLAGS_FB (1 << 12)
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/* The only fb_type we support is RGB. No text modes and no color palettes. */
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#define X86_MULTIBOOT_INFO_FB_TYPE_RGB 1
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#endif /* ZEPHYR_INCLUDE_ARCH_X86_MULTIBOOT_H_ */
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