99f4683adf
Masked ROMs are the silent killers of boot speed on devices without memory-mapped SPI flash. They often contain awfully slow SPI drivers (presumably bit-banged) that take hundreds of milliseconds to load our bootblock, and every extra kilobyte of bootblock size has a hugely disproportionate impact on boot speed. The coreboot timestamps can never show that component, but it impacts our users all the same. This patch tries to alleviate that issue a bit by allowing us to compress the bootblock with LZ4, which can cut its size down to nearly half. Of course, masked ROMs usually don't come with decompression algorithms built in, so we need to introduce a little decompression stub that can decompress the rest of the bootblock. This is done by creating a new "decompressor" stage which runs before the bootblock, but includes the compressed bootblock code in its data section. It needs to be as small as possible to get a real benefit from this approach, which means no device drivers, no console output, no exception handling, etc. Besides the decompression algorithm itself we only include the timer driver so that we can measure the boot speed impact of decompression. On ARM and ARM64 systems, we also need to give SoC code a chance to initialize the MMU, since running decompression without MMU is prohibitively slow on these architectures. This feature is implemented for ARM and ARM64 architectures for now, although most of it is architecture-independent and it should be relatively simple to port to other platforms where a masked ROM loads the bootblock into SRAM. It is also supposed to be a clean starting point from which later optimizations can hopefully cut down the decompression stub size (currently ~4K on RK3399) a bit more. NOTE: Bootblock compression is not for everyone. Possible side effects include trying to run LZ4 on CPUs that come out of reset extremely underclocked or enabling this too early in SoC bring-up and getting frustrated trying to find issues in an undebuggable environment. Ask your SoC vendor if bootblock compression is right for you. Change-Id: I0dc1cad9ae7508892e477739e743cd1afb5945e8 Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/26340 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Aaron Durbin <adurbin@chromium.org>
124 lines
3.7 KiB
C
124 lines
3.7 KiB
C
/*
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* This file is part of the coreboot project.
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*
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* Copyright 2014 Google Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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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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#ifndef __SYMBOLS_H
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#define __SYMBOLS_H
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#include <types.h>
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extern u8 _sram[];
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extern u8 _esram[];
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#define _sram_size (_esram - _sram)
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extern u8 _dram[];
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extern u8 _timestamp[];
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extern u8 _etimestamp[];
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#define _timestamp_size (_etimestamp - _timestamp)
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extern u8 _preram_cbmem_console[];
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extern u8 _epreram_cbmem_console[];
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#define _preram_cbmem_console_size \
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(_epreram_cbmem_console - _preram_cbmem_console)
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extern u8 _cbmem_init_hooks[];
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extern u8 _ecbmem_init_hooks[];
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#define _cbmem_init_hooks_size (_ecbmem_init_hooks - _cbmem_init_hooks)
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extern u8 _stack[];
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extern u8 _estack[];
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#define _stack_size (_estack - _stack)
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extern u8 _pagetables[];
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extern u8 _epagetables[];
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#define _pagetables_size (_epagetables - _pagetables)
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extern u8 _preram_cbfs_cache[];
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extern u8 _epreram_cbfs_cache[];
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#define _preram_cbfs_cache_size (_epreram_cbfs_cache - _preram_cbfs_cache)
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extern u8 _postram_cbfs_cache[];
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extern u8 _epostram_cbfs_cache[];
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#define _postram_cbfs_cache_size (_epostram_cbfs_cache - _postram_cbfs_cache)
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extern u8 _cbfs_cache[];
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extern u8 _ecbfs_cache[];
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#define _cbfs_cache_size (_ecbfs_cache - _cbfs_cache)
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extern u8 _payload[];
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extern u8 _epayload[];
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#define _payload_size (_epayload - _payload)
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/* "program" always refers to the current execution unit. */
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extern u8 _program[];
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extern u8 _eprogram[];
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#define _program_size (_eprogram - _program)
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/* _<stage>_size is always the maximum amount allocated in memlayout, whereas
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* _program_size gives the actual memory footprint *used* by current stage. */
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extern u8 _decompressor[];
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extern u8 _edecompressor[];
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#define _decompressor_size (_edecompressor - _decompressor)
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extern u8 _bootblock[];
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extern u8 _ebootblock[];
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#define _bootblock_size (_ebootblock - _bootblock)
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extern u8 _romstage[];
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extern u8 _eromstage[];
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#define _romstage_size (_eromstage - _romstage)
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extern u8 _ramstage[];
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extern u8 _eramstage[];
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#define _ramstage_size (_eramstage - _ramstage)
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extern u8 _verstage[];
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extern u8 _everstage[];
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#define _verstage_size (_everstage - _verstage)
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/* Arch-specific, move to <arch/symbols.h> if they become too many. */
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extern u8 _ttb[];
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extern u8 _ettb[];
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#define _ttb_size (_ettb - _ttb)
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extern u8 _ttb_subtables[];
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extern u8 _ettb_subtables[];
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#define _ttb_subtables_size (_ettb_subtables - _ttb_subtables)
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extern u8 _dma_coherent[];
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extern u8 _edma_coherent[];
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#define _dma_coherent_size (_edma_coherent - _dma_coherent)
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extern u8 _soc_registers[];
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extern u8 _esoc_registers[];
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#define _soc_registers_size (_esoc_registers - _soc_registers)
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extern u8 _framebuffer[];
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extern u8 _eframebuffer[];
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#define _framebuffer_size (_eframebuffer - _framebuffer)
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extern u8 _pdpt[];
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extern u8 _epdpt[];
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#define _pdpt_size (_epdpt - _pdpt)
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/* Put this into a .c file accessing a linker script region to mark that region
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* as "optional". If it is defined in memlayout.ld (or anywhere else), the
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* values from that definition will be used. If not, start, end and size will
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* all evaluate to 0. (We can't explicitly assign the symbols to 0 in the
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* assembly due to https://sourceware.org/bugzilla/show_bug.cgi?id=1038.) */
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#define DECLARE_OPTIONAL_REGION(name) asm (".weak _" #name ", _e" #name)
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#endif /* __SYMBOLS_H */
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