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Re: [PATCH] Improve ramdisk support

To: linux-mips@linux-mips.org
Subject: Re: [PATCH] Improve ramdisk support
From: Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>
Date: Sun, 21 Nov 2004 17:20:54 +0100
Cc: ralf@linux-mips.org
In-reply-to: <20041121030614.GL20986@rembrandt.csv.ica.uni-stuttgart.de>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20041121030614.GL20986@rembrandt.csv.ica.uni-stuttgart.de>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.6i
Thiemo Seufer wrote:
> Hello All,
> 
> there are currently two methods to use an initial ramdisk in the
> kernel, either by compiling it in via CONFIG_EMBEDDED_RAMDISK or by
> tacking the ramdisk on the kernel image via addinitrd. A third method
> currently under development is a compiled in cpio archive handled via
> initramfs.
> 
> There is, however, no way to add an initial ramdisk after the kernel
> was built. The appended patch introduces "rd_start" and "rd_size"
> command line parameters which allow a bootloader to preload the
> ramdisk and make its location known to the kernel by feeding
> appropriate rd_start/rd_size values.
> 
> Debian used an earlier version of this patch for several years now.

CONFIG_EMBEDDED_RAMDISK is gone now. The updated patch below removes
some leftovers.


Thiemo


Index: arch/mips/au1000/common/setup.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/au1000/common/setup.c,v
retrieving revision 1.20
diff -u -p -r1.20 setup.c
--- arch/mips/au1000/common/setup.c     11 Oct 2004 20:01:14 -0000      1.20
+++ arch/mips/au1000/common/setup.c     21 Nov 2004 16:14:03 -0000
@@ -42,11 +42,6 @@
 #include <asm/mach-au1x00/au1000.h>
 #include <asm/time.h>
 
-#ifdef CONFIG_BLK_DEV_INITRD
-extern unsigned long initrd_start, initrd_end;
-extern void * __rd_start, * __rd_end;
-#endif
-
 extern char * __init prom_getcmdline(void);
 extern void __init board_setup(void);
 extern void au1000_restart(char *);
@@ -153,12 +148,6 @@ static int __init au1x00_setup(void)
        iomem_resource.start = IOMEM_RESOURCE_START;
        iomem_resource.end = IOMEM_RESOURCE_END;
 
-#ifdef CONFIG_BLK_DEV_INITRD
-       ROOT_DEV = MKDEV(RAMDISK_MAJOR, 0);
-       initrd_start = (unsigned long)&__rd_start;
-       initrd_end = (unsigned long)&__rd_end;
-#endif
-
        while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_E0S);
        au_writel(SYS_CNTRL_E0 | SYS_CNTRL_EN0, SYS_COUNTER_CNTRL);
        au_sync();
Index: arch/mips/dec/setup.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/dec/setup.c,v
retrieving revision 1.41
diff -u -p -r1.41 setup.c
--- arch/mips/dec/setup.c       20 Aug 2004 09:19:01 -0000      1.41
+++ arch/mips/dec/setup.c       21 Nov 2004 16:14:03 -0000
@@ -48,11 +48,6 @@ extern irqreturn_t dec_intr_halt(int irq
 
 extern asmlinkage void decstation_handle_int(void);
 
-#ifdef CONFIG_BLK_DEV_INITRD
-extern unsigned long initrd_start, initrd_end;
-extern void * __rd_start, * __rd_end;
-#endif
-
 spinlock_t ioasic_ssr_lock;
 
 volatile u32 *ioasic_base;
@@ -136,11 +131,6 @@ extern void dec_timer_setup(struct irqac
 
 static void __init decstation_setup(void)
 {
-#ifdef CONFIG_BLK_DEV_INITRD
-       ROOT_DEV = MKDEV(RAMDISK_MAJOR, 0);
-       initrd_start = (unsigned long)&__rd_start;
-       initrd_end = (unsigned long)&__rd_end;
-#endif
        board_be_init = dec_be_init;
        board_time_init = dec_time_init;
        board_timer_setup = dec_timer_setup;
Index: arch/mips/dec/boot/decstation.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/dec/boot/decstation.c,v
retrieving revision 1.2
diff -u -p -r1.2 decstation.c
--- arch/mips/dec/boot/decstation.c     4 Jun 2003 18:14:26 -0000       1.2
+++ arch/mips/dec/boot/decstation.c     21 Nov 2004 16:14:03 -0000
@@ -26,7 +26,6 @@
 #define INITRD_SIZE (*(unsigned long *) (PARAM+0x21c))
 
 extern int _ftext, _end;               /* begin and end of kernel image */
-extern void *__rd_start, *__rd_end;    /* begin and end of ramdisk image */
 extern void kernel_entry(int, char **, unsigned long, int *);
 
 void * memcpy(void * dest, const void *src, unsigned int count)
@@ -81,11 +80,5 @@ void dec_entry(int argc, char **argv,
                rex_clear_cache();
        }
 
-#ifdef CONFIG_BLK_DEV_INITRD
-       LOADER_TYPE = 1;
-       INITRD_START = (long)&__rd_start;
-       INITRD_SIZE = (long)&__rd_end - (long)&__rd_start;
-#endif
-
        kernel_entry(argc, argv, magic, prom_vec);
 }
Index: arch/mips/jmr3927/rbhma3100/setup.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/jmr3927/rbhma3100/setup.c,v
retrieving revision 1.14
diff -u -p -r1.14 setup.c
--- arch/mips/jmr3927/rbhma3100/setup.c 20 Aug 2004 11:29:06 -0000      1.14
+++ arch/mips/jmr3927/rbhma3100/setup.c 21 Nov 2004 16:14:03 -0000
@@ -184,10 +184,6 @@ unsigned long jmr3927_do_gettimeoffset(v
 }
 
 
-#if defined(CONFIG_BLK_DEV_INITRD)
-extern unsigned long __rd_start, __rd_end, initrd_start, initrd_end;
-#endif
-
 //#undef DO_WRITE_THROUGH
 #define DO_WRITE_THROUGH
 #define DO_ENABLE_CACHE
Index: arch/mips/kernel/setup.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/kernel/setup.c,v
retrieving revision 1.171
diff -u -p -r1.171 setup.c
--- arch/mips/kernel/setup.c    28 Jun 2004 21:04:12 -0000      1.171
+++ arch/mips/kernel/setup.c    21 Nov 2004 16:14:03 -0000
@@ -56,8 +56,6 @@ unsigned int PCI_DMA_BUS_IS_PHYS;
 
 EXPORT_SYMBOL(PCI_DMA_BUS_IS_PHYS);
 
-extern void * __rd_start, * __rd_end;
-
 /*
  * Setup information
  *
@@ -194,6 +192,68 @@ static inline void parse_cmdline_early(v
        }
 }
 
+static inline int parse_rd_cmdline(unsigned long* rd_start, unsigned long* 
rd_end)
+{
+       /*
+        * "rd_start=0xNNNNNNNN" defines the memory address of an initrd
+        * "rd_size=0xNN" it's size
+        */
+       unsigned long start = 0;
+       unsigned long size = 0;
+       unsigned long end;
+       char cmd_line[CL_SIZE];
+       char *start_str;
+       char *size_str;
+       char *tmp;
+
+       strcpy(cmd_line, command_line);
+       *command_line = 0;
+       tmp = cmd_line;
+       /* Ignore "rd_start=" strings in other parameters. */
+       start_str = strstr(cmd_line, "rd_start=");
+       if (start_str && start_str != cmd_line && *(start_str - 1) != ' ')
+               start_str = strstr(start_str, " rd_start=");
+       while (start_str) {
+               if (start_str != cmd_line)
+                       strncat(command_line, tmp, start_str - tmp);
+               start = memparse(start_str + 9, &start_str);
+               tmp = start_str + 1;
+               start_str = strstr(start_str, " rd_start=");
+       }
+       if (*tmp)
+               strcat(command_line, tmp);
+
+       strcpy(cmd_line, command_line);
+       *command_line = 0;
+       tmp = cmd_line;
+       /* Ignore "rd_size" strings in other parameters. */
+       size_str = strstr(cmd_line, "rd_size=");
+       if (size_str && size_str != cmd_line && *(size_str - 1) != ' ')
+               size_str = strstr(size_str, " rd_size=");
+       while (size_str) {
+               if (size_str != cmd_line)
+                       strncat(command_line, tmp, size_str - tmp);
+               size = memparse(size_str + 8, &size_str);
+               tmp = size_str + 1;
+               size_str = strstr(size_str, " rd_size=");
+       }
+       if (*tmp)
+               strcat(command_line, tmp);
+
+#ifdef CONFIG_MIPS64
+       /* HACK: Guess if the sign extension was forgotten */
+       if (start > 0x0000000080000000 && start < 0x00000000ffffffff)
+               start |= 0xffffffff00000000;
+#endif
+
+       end = start + size;
+       if (start && end) {
+               *rd_start = start;
+               *rd_end = end;
+               return 1;
+       }
+       return 0;
+}
 
 #define PFN_UP(x)      (((x) + PAGE_SIZE - 1) >> PAGE_SHIFT)
 #define PFN_DOWN(x)    ((x) >> PAGE_SHIFT)
@@ -205,30 +265,42 @@ static inline void parse_cmdline_early(v
 static inline void bootmem_init(void)
 {
        unsigned long start_pfn;
+       unsigned long reserved_end = (unsigned long)&_end;
 #ifndef CONFIG_SGI_IP27
-       unsigned long bootmap_size, max_low_pfn, first_usable_pfn;
+       unsigned long first_usable_pfn;
+       unsigned long bootmap_size;
        int i;
 #endif
 #ifdef CONFIG_BLK_DEV_INITRD
-       unsigned long tmp;
-       unsigned long *initrd_header;
+       int initrd_reserve_bootmem = 0;
 
-       tmp = (((unsigned long)&_end + PAGE_SIZE-1) & PAGE_MASK) - 8;
-       if (tmp < (unsigned long)&_end)
-               tmp += PAGE_SIZE;
-       initrd_header = (unsigned long *)tmp;
-       if (initrd_header[0] == 0x494E5244) {
-               initrd_start = (unsigned long)&initrd_header[2];
-               initrd_end = initrd_start + initrd_header[1];
+       /* Board specific code should have set up initrd_start and initrd_end */
+       ROOT_DEV = Root_RAM0;
+       if (parse_rd_cmdline(&initrd_start, &initrd_end)) {
+               reserved_end = max(reserved_end, initrd_end);
+               initrd_reserve_bootmem = 1;
+       } else {
+               unsigned long tmp;
+               unsigned long *initrd_header;
+
+               tmp = ((reserved_end + PAGE_SIZE-1) & PAGE_MASK) - 8;
+               if (tmp < reserved_end)
+                       tmp += PAGE_SIZE;
+               initrd_header = (unsigned long *)tmp;
+               if (initrd_header[0] == 0x494E5244) {
+                       initrd_start = (unsigned long)&initrd_header[2];
+                       initrd_end = initrd_start + initrd_header[1];
+                       reserved_end = max(reserved_end, initrd_end);
+                       initrd_reserve_bootmem = 1;
+               }
        }
-       start_pfn = PFN_UP(CPHYSADDR((&_end)+(initrd_end - initrd_start) + 
PAGE_SIZE));
-#else
+#endif /* CONFIG_BLK_DEV_INITRD */
+
        /*
         * Partially used pages are not usable - thus
         * we are rounding upwards.
         */
-       start_pfn = PFN_UP(CPHYSADDR(&_end));
-#endif /* CONFIG_BLK_DEV_INITRD */
+       start_pfn = PFN_UP(CPHYSADDR(reserved_end));
 
 #ifndef CONFIG_SGI_IP27
        /* Find the highest page frame number we have available.  */
@@ -341,21 +413,14 @@ static inline void bootmem_init(void)
 
        /* Reserve the bootmap memory.  */
        reserve_bootmem(PFN_PHYS(first_usable_pfn), bootmap_size);
-#endif
+#endif /* CONFIG_SGI_IP27 */
 
 #ifdef CONFIG_BLK_DEV_INITRD
-       /* Board specific code should have set up initrd_start and initrd_end */
-       ROOT_DEV = Root_RAM0;
-       if (&__rd_start != &__rd_end) {
-               initrd_start = (unsigned long)&__rd_start;
-               initrd_end = (unsigned long)&__rd_end;
-       }
        initrd_below_start_ok = 1;
        if (initrd_start) {
                unsigned long initrd_size = ((unsigned char *)initrd_end) - 
((unsigned char *)initrd_start);
                printk("Initial ramdisk at: 0x%p (%lu bytes)\n",
-                      (void *)initrd_start,
-                      initrd_size);
+                      (void *)initrd_start, initrd_size);
 
                if (CPHYSADDR(initrd_end) > PFN_PHYS(max_low_pfn)) {
                        printk("initrd extends beyond end of memory "
@@ -363,7 +428,11 @@ static inline void bootmem_init(void)
                               sizeof(long) * 2, CPHYSADDR(initrd_end),
                               sizeof(long) * 2, PFN_PHYS(max_low_pfn));
                        initrd_start = initrd_end = 0;
+                       initrd_reserve_bootmem = 0;
                }
+
+               if (initrd_reserve_bootmem)
+                       reserve_bootmem(CPHYSADDR(initrd_start), initrd_size);
        }
 #endif /* CONFIG_BLK_DEV_INITRD  */
 }
Index: arch/mips/sibyte/cfe/setup.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/sibyte/cfe/setup.c,v
retrieving revision 1.19
diff -u -p -r1.19 setup.c
--- arch/mips/sibyte/cfe/setup.c        21 Nov 2004 13:50:35 -0000      1.19
+++ arch/mips/sibyte/cfe/setup.c        21 Nov 2004 16:14:04 -0000
@@ -56,7 +56,6 @@ int cfe_cons_handle;
 
 #ifdef CONFIG_BLK_DEV_INITRD
 extern unsigned long initrd_start, initrd_end;
-extern void * __rd_start, * __rd_end;
 #endif
 
 #ifdef CONFIG_KGDB
Index: arch/mips/sibyte/swarm/setup.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/sibyte/swarm/setup.c,v
retrieving revision 1.32
diff -u -p -r1.32 setup.c
--- arch/mips/sibyte/swarm/setup.c      14 Sep 2004 21:23:33 -0000      1.32
+++ arch/mips/sibyte/swarm/setup.c      21 Nov 2004 16:14:04 -0000
@@ -52,10 +52,6 @@ extern int m41t81_probe(void);
 extern int m41t81_set_time(unsigned long);
 extern unsigned long m41t81_get_time(void);
 
-#ifdef CONFIG_BLK_DEV_INITRD
-extern void * __rd_start, * __rd_end;
-#endif
-
 const char *get_system_type(void)
 {
        return "SiByte " SIBYTE_BOARD_NAME;

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