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/*
* vrl4 format generator
*
* Copyright (C) 2010 Simon Horman
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
/*
* usage: vrl4 < zImage > out
* dd if=out of=/dev/sdx bs=512 seek=1 # Write the image to sector 1
*
* Reads a zImage from stdin and writes a vrl4 image to stdout.
* In practice this means writing a padded vrl4 header to stdout followed
* by the zImage.
*
* The padding places the zImage at ALIGN bytes into the output.
* The vrl4 uses ALIGN + START_BASE as the start_address.
* This is where the mask ROM will jump to after verifying the header.
*
* The header sets copy_size to min(sizeof(zImage), MAX_BOOT_PROG_LEN) + ALIGN.
* That is, the mask ROM will load the padded header (ALIGN bytes)
* And then MAX_BOOT_PROG_LEN bytes of the image, or the entire image,
* whichever is smaller.
*
* The zImage is not modified in any way.
*/
#define _BSD_SOURCE
#include <endian.h>
#include <unistd.h>
#include <stdint.h>
#include <stdio.h>
#include <errno.h>
struct hdr {
uint32_t magic1;
uint32_t reserved1;
uint32_t magic2;
uint32_t reserved2;
uint16_t copy_size;
uint16_t boot_options;
uint32_t reserved3;
uint32_t start_address;
uint32_t reserved4;
uint32_t reserved5;
char reserved6[308];
};
#define DECLARE_HDR(h) \
struct hdr (h) = { \
.magic1 = htole32(0xea000000), \
.reserved1 = htole32(0x56), \
.magic2 = htole32(0xe59ff008), \
.reserved3 = htole16(0x1) }
/* Align to 512 bytes, the MMCIF sector size */
#define ALIGN_BITS 9
#define ALIGN (1 << ALIGN_BITS)
#define START_BASE 0xe55b0000
/*
* With an alignment of 512 the header uses the first sector.
* There is a 128 sector (64kbyte) limit on the data loaded by the mask ROM.
* So there are 127 sectors left for the boot programme. But in practice
* Only a small portion of a zImage is needed, 16 sectors should be more
* than enough.
*
* Note that this sets how much of the zImage is copied by the mask ROM.
* The entire zImage is present after the header and is loaded
* by the code in the boot program (which is the first portion of the zImage).
*/
#define MAX_BOOT_PROG_LEN (16 * 512)
#define ROUND_UP(x) ((x + ALIGN - 1) & ~(ALIGN - 1))
ssize_t do_read(int fd, void *buf, size_t count)
{
size_t offset = 0;
ssize_t l;
while (offset < count) {
l = read(fd, buf + offset, count - offset);
if (!l)
break;
if (l < 0) {
if (errno == EAGAIN || errno == EWOULDBLOCK)
continue;
perror("read");
return -1;
}
offset += l;
}
return offset;
}
ssize_t do_write(int fd, const void *buf, size_t count)
{
size_t offset = 0;
ssize_t l;
while (offset < count) {
l = write(fd, buf + offset, count - offset);
if (l < 0) {
if (errno == EAGAIN || errno == EWOULDBLOCK)
continue;
perror("write");
return -1;
}
offset += l;
}
return offset;
}
ssize_t write_zero(int fd, size_t len)
{
size_t i = len;
while (i--) {
const char x = 0;
if (do_write(fd, &x, 1) < 0)
return -1;
}
return len;
}
int main(void)
{
DECLARE_HDR(hdr);
char boot_program[MAX_BOOT_PROG_LEN];
size_t aligned_hdr_len, alligned_prog_len;
ssize_t prog_len;
prog_len = do_read(0, boot_program, sizeof(boot_program));
if (prog_len <= 0)
return -1;
aligned_hdr_len = ROUND_UP(sizeof(hdr));
hdr.start_address = htole32(START_BASE + aligned_hdr_len);
alligned_prog_len = ROUND_UP(prog_len);
hdr.copy_size = htole16(aligned_hdr_len + alligned_prog_len);
if (do_write(1, &hdr, sizeof(hdr)) < 0)
return -1;
if (write_zero(1, aligned_hdr_len - sizeof(hdr)) < 0)
return -1;
if (do_write(1, boot_program, prog_len) < 0)
return 1;
/* Write out the rest of the kernel */
while (1) {
prog_len = do_read(0, boot_program, sizeof(boot_program));
if (prog_len < 0)
return 1;
if (prog_len == 0)
break;
if (do_write(1, boot_program, prog_len) < 0)
return 1;
}
return 0;
}
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