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https://github.com/brain-hackers/u-boot-brain
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9e6c572ff0
Use the base address of the 'F' segment as a pointer to the global data structure. By adding the linear address (i.e. the 'D' segment address) as the first word of the global data structure, the address of the global data relative to the 'D' segment can be found simply, for example, by: fs movl 0, %eax This makes the gd 'pointer' writable prior to relocation (by reloading the Global Desctriptor Table) which brings x86 into line with all other arches NOTE: Writing to the gd 'pointer' is expensive (but we only do it twice) but using it to access global data members (read and write) is still fairly cheap -- Changes for v2: - Rebased against changes made to patch #3 - Removed extra indent - Tweaked commit message
92 lines
3.2 KiB
C
92 lines
3.2 KiB
C
/*
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* (C) Copyright 2002-2010
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* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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#ifndef __ASM_GBL_DATA_H
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#define __ASM_GBL_DATA_H
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/*
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* The following data structure is placed in some memory wich is
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* available very early after boot (like DPRAM on MPC8xx/MPC82xx, or
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* some locked parts of the data cache) to allow for a minimum set of
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* global variables during system initialization (until we have set
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* up the memory controller so that we can use RAM).
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*
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* Keep it *SMALL* and remember to set GENERATED_GBL_DATA_SIZE > sizeof(gd_t)
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*/
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#ifndef __ASSEMBLY__
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typedef struct global_data {
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/* NOTE: gd_addr MUST be first member of struct global_data! */
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unsigned long gd_addr; /* Location of Global Data */
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bd_t *bd;
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unsigned long flags;
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unsigned long baudrate;
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unsigned long have_console; /* serial_init() was called */
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#ifdef CONFIG_PRE_CONSOLE_BUFFER
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unsigned long precon_buf_idx; /* Pre-Console buffer index */
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#endif
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unsigned long reloc_off; /* Relocation Offset */
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unsigned long load_off; /* Load Offset */
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unsigned long env_addr; /* Address of Environment struct */
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unsigned long env_valid; /* Checksum of Environment valid? */
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unsigned long cpu_clk; /* CPU clock in Hz! */
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unsigned long bus_clk;
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unsigned long relocaddr; /* Start address of U-Boot in RAM */
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unsigned long start_addr_sp; /* start_addr_stackpointer */
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unsigned long gdt_addr; /* Location of GDT */
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unsigned long new_gd_addr; /* New location of Global Data */
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phys_size_t ram_size; /* RAM size */
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unsigned long reset_status; /* reset status register at boot */
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void **jt; /* jump table */
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char env_buf[32]; /* buffer for getenv() before reloc. */
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} gd_t;
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static inline gd_t *get_fs_gd_ptr(void)
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{
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gd_t *gd_ptr;
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asm volatile("fs movl 0, %0\n" : "=r" (gd_ptr));
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return gd_ptr;
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}
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#define gd get_fs_gd_ptr()
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#endif
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/*
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* Global Data Flags
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*/
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#define GD_FLG_RELOC 0x00001 /* Code was relocated to RAM */
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#define GD_FLG_DEVINIT 0x00002 /* Devices have been initialized */
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#define GD_FLG_SILENT 0x00004 /* Silent mode */
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#define GD_FLG_POSTFAIL 0x00008 /* Critical POST test failed */
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#define GD_FLG_POSTSTOP 0x00010 /* POST seqeunce aborted */
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#define GD_FLG_LOGINIT 0x00020 /* Log Buffer has been initialized */
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#define GD_FLG_DISABLE_CONSOLE 0x00040 /* Disable console (in & out) */
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#define GD_FLG_ENV_READY 0x00080 /* Environment imported into hash table */
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#define DECLARE_GLOBAL_DATA_PTR
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#endif /* __ASM_GBL_DATA_H */
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