On Thu, May 11, 2023 at 09:25:12AM +0200, Sascha Hauer wrote: > On Thu, May 11, 2023 at 01:37:01AM +0200, Jules Maselbas wrote: > > On power-up Allwinner SoC starts in boot ROM, aka BROM, which will search > > for an eGON image: first from the SD card, then from eMMC. If no image is > > found then the BROM will enter into FEL mode that can be used for initial > > programming and recovery of devices using USB. > > > > The eGON header structure is adapted from u-boot: /include/sunxi_image.h, > > the header structure is also documented on https://linux-sunxi.org/EGON > > > > BROM will load, at most, the first 32KB of the image into SRAM, including > > the header itself! The jump instruction in the header needs to be patched > > accordingly with the image size. > > Do I understand it correctly that all code needed to load the full > barebox image needs to fit into these 32KiB? Yes, this is done by the "xload" PBL-only image. But for developpement I load code through USB to a different SRAM of 108KB! > Where must this image be placed? Directly at the origin of the SD card? > That would mean the partition table is somewhere inside the binary, > right? The eGON image must start exactly at 8KB offset from the origin of the SD card. This leave room for the actual partition table. > > > + > > +#define ALIGN(x, a) __ALIGN_MASK(x, (typeof(x))(a) - 1) > > +#define __ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask)) > > You can reuse the definition of these in scripts/include/linux/kernel.h Ack > > +#define STAMP_VALUE 0x5f0a6c39 > > + > > +static void mkimage(char *infile, char *outfile) > > +{ > > + struct egon_header *hdr; > > + uint32_t *p32; > > + uint32_t sum; > > + int i; > > + size_t hdr_size; > > + size_t bin_size; > > + size_t img_size; > > + char *bin; > > + int fd, ret; > > + > > + bin = read_file(infile, &bin_size); > > + if (!bin) { > > + perror("read_file"); > > + exit(1); > > + } > > + > > + /* the header must be a multiple of 32 bytes */ > > + hdr_size = sizeof(*hdr); > > + > > + /* test if the binary has reserved space for the header */ > > + hdr = (void *)bin; > > Declare bin as void *, this makes the explicit cast unnecessary. > > > + if (hdr->branch == EGON_HDR_BRANCH && memcmp(hdr->magic, "eGON", 4) == 0) { > > + /* strip the existing header */ > > + bin += hdr_size; > > + bin_size -= hdr_size; > > + } > > + hdr = calloc(1, hdr_size); > > + if (!hdr) { > > + perror("malloc"); > > + exit(1); > > + } > > + > > + /* The total image length must be a multiple of 4K bytes */ > > + img_size = ALIGN(hdr_size + bin_size, 4096); > > + > > + hdr->check_sum = 0; > > hdr is already zeroed due to the use of calloc. Yes, i don't recall why I did this... I don't exactly recall how the checksum is verified by the boot rom. > > + hdr->branch = EGON_HDR_BRANCH; > > + hdr->length = cpu_to_le32(img_size); > > + memcpy(hdr->magic, "eGON.BT0", 8); > > + memcpy(hdr->spl_signature, "SPL", 3); > > + hdr->spl_signature[3] = 0x03; /* version 0.3 */ > > + > > + /* calculate the checksum */ > > + sum = STAMP_VALUE; > > + for (p32 = (void *) hdr, i = 0; i < hdr_size / sizeof(uint32_t); i++) > > + sum += le32_to_cpu(p32[i]); > > + for (p32 = (void *) bin, i = 0; i < bin_size / sizeof(uint32_t); i++) > > + sum += le32_to_cpu(p32[i]); > > Does this work when bin_size is not a multiple of sizeof(uint32_t)? > It likely is, but who knows... bin_size should be a multiple of sizeof(uint32_t), if that's not the case I don't think that the result will be correct. But I could add something to handle this exact case. > You are calculating the checksum up to bin_size, not including the final > alignment. That works because the alignment is filled with 0x0 which > doesn't add to this checksum. That is ok, but maybe it's worth noting > that in the code. Yes you're right, I'll add a comment, and also on ftruncate that is used to pad the image with zero. > > Sascha > > -- > Pengutronix e.K. | | > Steuerwalder Str. 21 | http://www.pengutronix.de/ | > 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | >
