I would like to use a directory as initrd file without
having to write it to an initrd file each time I have
changed anything in that directory.
I have written code to pipe an initrd directly from cpio
to qemu. Do you have any feedback on the attached patch?
--
Kasper Dupont -- Rigtige mænd skriver deres egne backupprogrammer
#define _(_)"d.%.4s%."_"2s" /* This is my email address */
char*_="@2kaspner"_()"%03"_("4s%.")"t\n";printf(_+11,_+6,_,12,_+2,_+7,_+6);
diff -up qemu-2.0.0+dfsg/hw/core/loader.c.orig qemu-2.0.0+dfsg/hw/core/loader.c
--- qemu-2.0.0+dfsg/hw/core/loader.c.orig 2014-04-17 15:30:59.000000000
+0200
+++ qemu-2.0.0+dfsg/hw/core/loader.c 2016-01-17 19:38:01.505138214 +0100
@@ -137,6 +137,70 @@ void pstrcpy_targphys(const char *name,
}
}
+/* return the size or -1 if error */
+int load_initrd(const char *filename, uint8_t **addr)
+{
+ pid_t child = 0;
+ int fd, size = 0, buffer_size = 4096;
+ fd = open(filename, O_RDONLY | O_BINARY);
+ if (fd < 0)
+ return -1;
+
+ *addr = malloc(buffer_size);
+
+ while(*addr) {
+ int bytes_read = read(fd, (*addr) + size, buffer_size - size);
+
+ if (bytes_read == 0) {
+ close(fd);
+ if (child) {
+ waitpid(child, NULL, 0);
+ }
+ return size;
+ }
+
+ if (bytes_read > 0) {
+ size += bytes_read;
+ } else {
+ int pipefd[2];
+
+ if (errno != EISDIR)
+ return -1;
+
+ assert(!child);
+
+ if (pipe(pipefd))
+ return -1;
+
+ child = fork();
+ if (child == -1)
+ return -1;
+
+ if (!child) {
+ if(fchdir(fd))
+ error(1, errno, "fchdir failed");
+ if(dup2(pipefd[1], 1) == -1)
+ error(1, errno, "dup2 failed");
+ execlp("/bin/sh", "/bin/sh", "-c",
+ "find . | cpio --quiet -R 0:0 -o -H newc",
+ NULL);
+ error(1, errno, "/bin/sh");
+ }
+
+ close(fd);
+ close(pipefd[1]);
+ fd = pipefd[0];
+ }
+
+ if (size == buffer_size) {
+ buffer_size <<= 1;
+ *addr = realloc(*addr, buffer_size);
+ }
+ }
+
+ return -1;
+}
+
/* A.OUT loader */
struct exec
diff -up qemu-2.0.0+dfsg/hw/i386/pc.c.orig qemu-2.0.0+dfsg/hw/i386/pc.c
--- qemu-2.0.0+dfsg/hw/i386/pc.c.orig 2014-04-17 15:30:59.000000000 +0200
+++ qemu-2.0.0+dfsg/hw/i386/pc.c 2016-01-17 19:16:04.704258817 +0100
@@ -829,12 +829,13 @@ static void load_linux(FWCfgState *fw_cf
/* load initrd */
if (initrd_filename) {
+ uint8_t *initrd_load_buffer;
if (protocol < 0x200) {
fprintf(stderr, "qemu: linux kernel too old to load a ram disk\n");
exit(1);
}
- initrd_size = get_image_size(initrd_filename);
+ initrd_size = load_initrd(initrd_filename, &initrd_load_buffer);
if (initrd_size < 0) {
fprintf(stderr, "qemu: error reading initrd %s: %s\n",
initrd_filename, strerror(errno));
@@ -844,7 +845,8 @@ static void load_linux(FWCfgState *fw_cf
initrd_addr = (initrd_max-initrd_size) & ~4095;
initrd_data = g_malloc(initrd_size);
- load_image(initrd_filename, initrd_data);
+ memcpy(initrd_data, initrd_load_buffer, initrd_size);
+ free(initrd_load_buffer);
fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_ADDR, initrd_addr);
fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_SIZE, initrd_size);
diff -up qemu-2.0.0+dfsg/include/hw/loader.h.orig
qemu-2.0.0+dfsg/include/hw/loader.h
--- qemu-2.0.0+dfsg/include/hw/loader.h.orig 2014-04-17 15:30:59.000000000
+0200
+++ qemu-2.0.0+dfsg/include/hw/loader.h 2016-01-17 19:15:30.688236909 +0100
@@ -13,6 +13,7 @@
*/
int get_image_size(const char *filename);
int load_image(const char *filename, uint8_t *addr); /* deprecated */
+int load_initrd(const char *filename, uint8_t **addr);
int load_image_targphys(const char *filename, hwaddr,
uint64_t max_sz);
