[PATCH] PPC64: large INITRD causes kernel not to boot

Mark Bellon
2005-08-08T17:55:38Z

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In PPC64 there are number of problems in arch/ppc64/boot/main.c that
prevent a kernel from making use of a large (greater than ~16MB) INITRD.
This is 64 bit architecture and really large INITRD images should be
possible.

Simply put the existing code has a fixed reservation (claim) address and
once the kernel plus initrd image are large enough to pass this address
all sorts of bad things occur. The fix is the dynamically establish the
first claim address above the loaded kernel plus initrd (plus some
"padding" and rounding)

mark

Signed-off-by: Mark Bellon <mbellon@mvista.com>

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Index: linux-2.6.12.3/arch/ppc64/boot/main.c
===================================================================
--- linux-2.6.12.3.orig/arch/ppc64/boot/main.c
+++ linux-2.6.12.3/arch/ppc64/boot/main.c
@@ -22,7 +22,7 @@
extern void printf(const char *fmt, ...);
extern int sprintf(char *buf, const char *fmt, ...);
void gunzip(void *, int, unsigned char *, int *);
-void *claim(unsigned int, unsigned int, unsigned int);
+void *claim(unsigned long, unsigned long, unsigned long);
void flush_cache(void *, unsigned long);
void pause(void);
extern void exit(void);
@@ -31,9 +31,8 @@
void *memmove(void *dest, const void *src, unsigned long n);
void *memcpy(void *dest, const void *src, unsigned long n);

-/* Value picked to match that used by yaboot */
-#define PROG_START 0x01400000
-#define RAM_END (256<<20) // Fixme: use OF */
+#define ONE_MB 0x100000
+#define RAM_END (512<<20) // Fixme: use OF */

char *avail_ram;
char *begin_avail, *end_avail;
@@ -75,13 +74,13 @@

#define DEBUG

-static unsigned long claim_base = PROG_START;
+static unsigned long claim_base;

static unsigned long try_claim(unsigned long size)
{
unsigned long addr = 0;

- for(; claim_base < RAM_END; claim_base += 0x100000) {
+ for(; claim_base < RAM_END; claim_base += ONE_MB) {
#ifdef DEBUG
printf(" trying: 0x%08lx\n\r", claim_base);
#endif
@@ -112,7 +111,23 @@
if (getprop(chosen_handle, "stdin", &stdin, sizeof(stdin)) != 4)
exit();

- printf("zImage starting: loaded at 0x%x\n\r", (unsigned)_start);
+ printf("zImage starting: loaded at 0x%lx\n\r", (unsigned long)_start);
+
+ /*
+ * The first available claim_base must be "out of the way" -
+ * well above _start + kernel_size + initrd + overhead.
+ */
+
+ claim_base = ((unsigned long) _start) +
+ ((unsigned long) vmlinux_filesize) +
+ (unsigned long)(_initrd_end - _initrd_start) +
+ ONE_MB;
+
+ /*
+ * Now round up the claim_base to a nice 1 MB boundary.
+ */
+
+ claim_base = ((claim_base + ONE_MB - 1) / ONE_MB) * ONE_MB;

/*
* Now we try to claim some memory for the kernel itself
@@ -122,7 +137,7 @@
* size... In practice we add 1Mb, that is enough, but we should really
* consider fixing the Makefile to put a _raw_ kernel in there !
*/
- vmlinux_memsize += 0x100000;
+ vmlinux_memsize += ONE_MB;
printf("Allocating 0x%lx bytes for kernel ...\n\r", vmlinux_memsize);
vmlinux.addr = try_claim(vmlinux_memsize);
if (vmlinux.addr == 0) {