Hi Graeme,
On Thu, Dec 22, 2011 at 3:27 AM, Graeme Russ <graeme.r...@gmail.com> wrote:
> Hi Simon,
>
> On 22/12/11 17:44, Simon Glass wrote:
>> Hi Graeme,
>>
>> On Tue, Dec 20, 2011 at 4:06 AM, Graeme Russ <graeme.r...@gmail.com> wrote:
>>> With Simon's work on generic relocation support, I thought I would throw in
>>> what I am planning for arch/x86/lib/board.c
>>>
>>> Now this is not a patch, it is a work-in-progress complete version of the
>>> file (compiles, will test soon) - If feedback is positive, I'll add this to
>>> an upcoming patch set
>>
>> Looks good to me+++
>
> Thanks for having a look :)
>
>>> Notice the amount of wrapping around void functions - If all other arch's
>>> follow this lead, most of this wrapping can be removed by changing the
>>> function signatures.
>>>
>>> Lines 428 - 585 are effectively the generic init sequence - The rest is
>>> wrappers, init sequence arrays, or fluff that should be moved
>>>
>>> I noticed something along the way - gd is no longer special... let me
>>> explain...
>>>
>>> Some arch's use a dedicated register for the gd pointer - This allows the
>>> pointer to be written to prior to relocation. For x86, the gd pointer is
>>> simply passed around as a function parameter early - If the init_sequence_f
>>> functions accepted a gd pointer as a parameter, there would be no need for
>>> it to be global prior to relocation and therefore no need to allocate a
>>> permanent register for it - Of course do_init_loop() would no longer be
>>> generic for both pre and post relocation. This does mess with the
>>> stand-alone API, but as discussed before, stand alone applications should
>>> not be accessing gd anyway, so there should be no API to break ;)
>>
>> Actually as it happens I did a bit of an experiment with this some
>> weeks ago and my original board stuff had gd as a parameter for the
>> pre-reloc functions (some with stubs to other ones like
>> console_init_f()). On ARM it really doesn't make a lot of sense to use
>> a global variable instead of a parameter. I decided that it was a bit
>> much to bite off in one go :-) Partly that was because IMO gd really
>> only makes sense prior to relocation - for the post-relocation init
>> calls they don't have a lot of need for gd.
>
> I don't think this is 100% correct - I'm sure gd is used all over the place
> post init
Not enough that it needs to be in its own register. This compile-time
decision affects the whole of U-Boot post-relocation. In some routines
there is a small code size / performance advantage to having r8
available.
Also it is a bit of a misnomer when used after relocation. There is
lots of global data (the whole BSS) not just one structure. Arguably
some things like the network code would be smaller/faster using
global_data and without total reliance on global variables, but anyway
it seems to me that gd is mostly a convenience for pre-relocation
where memory may not be available.
>
>> So it has my vote. Once I get somewhere on the reboard series I will
>> post my common/board.c. As I may have mentioned I have elected so far
>> to leave the initcall list and local functions in
>> arch/xxx/lib/board.c.
>>
>> Would be good to get all this moving.
>
> Well, I have a more thorough patch in the making - I creates
> init_wrappers.c and init_helpers.c and board.c collapses very dramatically
> (see below) - with a lot of #ifdef hell...
I thing that all pre-reloc functions that are called should have the
same signature - i.e. return an int. if we (later) move to passing gd
around then they would change in that way also.
>
> Notice the new board_init_f_r() - This is where U-Boot is running from
> Flash, but SDRAM has been initialised and the stack is now in RAM - So this
> is where we move gd to RAM and perform relocation. As a bonus, relocation
> can be done with cache enabled :)
Yes I see. It is not so easy on ARM since we need the MMU also, but I
think it can be done. Once data is set up / copied in its new location
we can use it even prior to relocation. I also recently created a
patch to delay console init until after relocation (cue screams on the
list) which saves time.
Regards,
Simon
>
> Regards,
>
> Graeme
>
>
>
> /*
> * (C) Copyright 2008-2011
> * Graeme Russ, <graeme.r...@gmail.com>
> *
> * (C) Copyright 2002
> * Daniel Engström, Omicron Ceti AB, <dan...@omicron.se>
> *
> * (C) Copyright 2002
> * Wolfgang Denk, DENX Software Engineering, <w...@denx.de>
> *
> * (C) Copyright 2002
> * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
> * Marius Groeger <mgroe...@sysgo.de>
> *
> * See file CREDITS for list of people who contributed to this
> * project.
> *
> * This program is free software; you can redistribute it and/or
> * modify it under the terms of the GNU General Public License as
> * published by the Free Software Foundation; either version 2 of
> * the License, or (at your option) any later version.
> *
> * This program is distributed in the hope that it will be useful,
> * but WITHOUT ANY WARRANTY; without even the implied warranty of
> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> * GNU General Public License for more details.
> *
> * You should have received a copy of the GNU General Public License
> * along with this program; if not, write to the Free Software
> * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> * MA 02111-1307 USA
> */
>
> #include <common.h>
> #include <watchdog.h>
> #include <stdio_dev.h>
> #include <asm/u-boot-x86.h>
>
> #include <asm/init_helpers.h>
> #include <asm/init_wrappers.h>
>
> /*
> * Pointer to initial global data area
> *
> * Here we initialize it.
> */
> #undef XTRN_DECLARE_GLOBAL_DATA_PTR
> #define XTRN_DECLARE_GLOBAL_DATA_PTR /* empty = allocate here */
> DECLARE_GLOBAL_DATA_PTR = (gd_t *) (CONFIG_SYS_INIT_GD_ADDR);
>
> /*
> * Breath some life into the board...
> *
> * Initialize an SMC for serial comms, and carry out some hardware
> * tests.
> *
> * The first part of initialization is running from Flash memory;
> * its main purpose is to initialize the RAM so that we
> * can relocate the monitor code to RAM.
> */
>
> /*
> * All attempts to come up with a "common" initialization sequence
> * that works for all boards and architectures failed: some of the
> * requirements are just _too_ different. To get rid of the resulting
> * mess of board dependend #ifdef'ed code we now make the whole
> * initialization sequence configurable to the user.
> *
> * The requirements for any new initalization function is simple: it
> * receives a pointer to the "global data" structure as it's only
> * argument, and returns an integer return code, where 0 means
> * "continue" and != 0 means "fatal error, hang the system".
> */
> typedef int (init_fnc_t) (void);
>
> init_fnc_t *init_sequence_f[] = {
> cpu_init_f,
> board_early_init_f,
> env_init,
> init_baudrate_f,
> serial_init,
> console_init_f,
> dram_init_f,
>
> NULL,
> };
>
> init_fnc_t *init_sequence_r[] = {
> init_bd_struct_r,
> mem_malloc_init_r,
> cpu_init_r,
> board_early_init_r,
> dram_init,
> interrupt_init,
> timer_init,
> display_banner,
> display_dram_config,
> #ifdef CONFIG_SERIAL_MULTI
> serial_initialize_r,
> #endif
> #ifndef CONFIG_SYS_NO_FLASH
> flash_init_r,
> #endif
> env_relocate_r,
> #ifdef CONFIG_CMD_NET
> init_ip_address_r,
> #endif
> #ifdef CONFIG_PCI
> pci_init_r,
> #endif
> stdio_init,
> jumptable_init_r,
> console_init_r,
> #ifdef CONFIG_MISC_INIT_R
> misc_init_r,
> #endif
> #if defined(CONFIG_CMD_PCMCIA) && !defined(CONFIG_CMD_IDE)
> pci_init_r,
> #endif
> #if defined(CONFIG_CMD_KGDB)
> kgdb_init_r,
> #endif
> enable_interrupts_r,
> #ifdef CONFIG_STATUS_LED
> status_led_set_r,
> #endif
> set_load_addr_r,
> #if defined(CONFIG_CMD_NET)
> set_bootfile_r,
> #endif
> #if defined(CONFIG_CMD_IDE)
> ide_init_r,
> #endif
> #if defined(CONFIG_CMD_SCSI)
> scsi_init_r,
> #endif
> #if defined(CONFIG_CMD_DOC)
> doc_init_r,
> #endif
> #ifdef CONFIG_BITBANGMII
> bb_miiphy_init_r,
> #endif
> #if defined(CONFIG_CMD_NET)
> eth_initialize_r,
> #ifdef CONFIG_RESET_PHY_R
> reset_phy_r,
> #endif
> #endif
> #ifdef CONFIG_LAST_STAGE_INIT
> last_stage_init,
> #endif
> NULL,
> };
>
> static void do_init_loop(init_fnc_t **init_fnc_ptr)
> {
> for (; *init_fnc_ptr; ++init_fnc_ptr) {
> WATCHDOG_RESET();
> if ((*init_fnc_ptr)() != 0)
> hang();
> }
> }
>
> /* Perform all steps necessary to get RAM initialised ready for relocation */
> void board_init_f(ulong boot_flags)
> {
> gd->flags = boot_flags;
>
> do_init_loop(init_sequence_f);
>
> /*
> * SDRAM is now initialised setup a new stack in SDRAM
> *
> * Code execution will continue in Flash, but with the stack
> * in SDRAM. This allows us to copy global data out of the CPU
> * cache prior to copying U-Boot into RAM which means we can
> * enable caching for the copy operation (which speeds it up
> * considerably)
> */
> move_stack_to_sdram(gd->ram_size);
>
> /* NOTREACHED - move_stack_to_sdram() does not return */
> while (1)
> ;
> }
>
> void board_init_f_r(gd_t *id)
> {
> /*
> * U-Boot is running from flash, but the stack is now in SDRAM
> * (id = top of stack = final location of global data)
> */
>
> /*
> * gd is still in CAR - Copy it into SDRAM
> *
> * NOTE: We cannot set the gd variable yet as it lives in .data
> * which has not been relocated to RAM yet
> */
> memcpy(id, gd, sizeof(gd_t));
>
> /* Initialise the CPU cache(s) */
> if (init_cache() != 0)
> hang();
>
> /* Copy U-Boot to RAM and resume code execution in RAM */
> relocate_code(0, id, 0);
>
> /* NOTREACHED - relocate_code() does not return */
> while (1)
> ;
> }
>
> __attribute__ ((__noreturn__))
> void board_init_r(gd_t *id, ulong dest_addr)
> {
> /* Global data pointer is now writable */
> gd = id;
>
> gd->flags |= GD_FLG_RELOC;
>
> /* compiler optimization barrier needed for GCC >= 3.4 */
> __asm__ __volatile__("" : : : "memory");
>
> do_init_loop(init_sequence_r);
>
> /* main_loop() can return to retry autoboot, if so just run it again.
> */
> for (;;)
> main_loop();
>
> /* NOTREACHED - no way out of command loop except booting */
> }
>
> __attribute__ ((__noreturn__))
> void hang(void)
> {
> puts("### ERROR ### Please RESET the board ###\n");
> for (;;)
> ;
> }
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