On Wed, Mar 13, 2019 at 10:18:06AM +0100, Heiko Schocher wrote: > Hello Stefano, > > Am 13.03.2019 um 09:51 schrieb Stefano Babic: > >Hi Heiko, > > > >On 13/03/19 08:44, Heiko Schocher wrote: > >>Hello Wolfgang, > >> > >>Am 12.03.2019 um 18:46 schrieb Wolfgang Denk: > >>>Dear Tom, > >>> > >>>In message <20190312173125.GP4690@bill-the-cat> you wrote: > >>>> > >>>>>I think you were misled by Heiko's description. What he really ment > >>>>>was just that the addresses where the boot ROM stored the > >>>>>information about the boot device etc. gets overwriteen when the SPL > >>>> > >>>>For clarity, that's not _quite_ it. The ROM passes the value in a > >>>>register and we move that to scratch space, see > >>>>arch/arm/mach-omap2/lowlevel_init.S and save_boot_params. This is done > >>>>on every 32bit Cortex-A TI platform. > >>>... > >>>>OK, but here's the problem. We define off, iirc, 1KiB of that SRAM > >>>>space as not-stack but scratch space to store stuff in. The first > >>>>problem you will hit, if something else touches that scratch space is > >>>>what Heiko found, the boot value got blown away. > >>> > >>>I see. Well, I think it's best if Heiko explains in detail; what he > >>>has observed, and what when which part of the information got lost. > >>>I was just interpreting his mail, so I may easily have misunderstood > >>>this. > >>> > >>>@ Heiko: Can you please elucidate? > >> > >>arch/arm/include/asm/arch-am33xx/omap.h > >> > >> 19 #ifdef CONFIG_AM33XX > >> 20 #define NON_SECURE_SRAM_START 0x402F0400 > >> 21 #define NON_SECURE_SRAM_END 0x40310000 > >> 22 #define NON_SECURE_SRAM_IMG_END 0x4030B800 > >> 23 #elif defined(CONFIG_TI816X) || defined(CONFIG_TI814X) > >> 24 #define NON_SECURE_SRAM_START 0x40300000 > >> 25 #define NON_SECURE_SRAM_END 0x40320000 > >> 26 #define NON_SECURE_SRAM_IMG_END 0x4031B800 > >> 27 #elif defined(CONFIG_AM43XX) > >> 28 #define NON_SECURE_SRAM_START 0x402F0400 > >> 29 #define NON_SECURE_SRAM_END 0x40340000 > >> 30 #define NON_SECURE_SRAM_IMG_END 0x40337DE0 > >> 31 #define QSPI_BASE 0x47900000 > >> 32 #endif > >> 33 #define SRAM_SCRATCH_SPACE_ADDR (NON_SECURE_SRAM_IMG_END - SZ_1K) > >> 34 > >> > >> > >>and with ./include/configs/ti_armv7_common.h > >> > >> 69 #ifndef CONFIG_SYS_INIT_SP_ADDR > >> 70 #define CONFIG_SYS_INIT_SP_ADDR (NON_SECURE_SRAM_END - \ > >> 71 > >>GENERATED_GBL_DATA_SIZE) > >> 72 #endif > >> 73 > >> > >>include/generated/generic-asm-offsets.h > >> > >> 9 #define GENERATED_GBL_DATA_SIZE 224 /* (sizeof(struct global_data) + > >>15) & ~15 @ */ > >> 10 #define GENERATED_BD_INFO_SIZE 112 /* (sizeof(struct bd_info) + 15) > >>& ~15 @ */ > >> 11 #define GD_SIZE 224 /* sizeof(struct global_data) @ */ > >> > >> > >>-> CONFIG_SYS_INIT_SP_ADDR = 0x40340000 - 0xe0 = 0x4033ff20 > >>-> SRAM_SCRATCH_SPACE_ADDR = 0x40337DE0 - 0x400 = 0x403379e0 > >> > >>./arch/arm/include/asm/omap_common.h: > >>816 #define OMAP_SRAM_SCRATCH_BOOT_PARAMS (SRAM_SCRATCH_SPACE_ADDR + > >>0x24) > >> > >>OMAP_SRAM_SCRATCH_BOOT_PARAMS = 0x40337a04 > >> > >>So stack is on a higher address than the scratch space. Stack > >>addresses decrement on usage, so may they overwrite scratch > >>space, as SPL functionality grows more and more ... > > > >What about to move this area after the initial SP ? This is the same way > >we do with GENERATED_GBL_DATA_SIZE to avoid to be overwritten. > > If I am not wrong, the value of SRAM_SCRATCH_SPACE_ADDR is not changeable > as it comes from the ROM bootloader.
No, we define the scratch space, but there's important restrictions. -- Tom
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