Re: [Qemu-devel] [PATCH] Increase max -kernel size

[Daniel Jacobowitz <drow@false.org>]

On Wed, Mar 28, 2007 at 03:00:08PM +0100, Paul Brook wrote:
> On Wednesday 28 March 2007 03:21, Daniel Jacobowitz wrote:
> > On Wed, Mar 28, 2007 at 12:35:18AM +0100, Thiemo Seufer wrote:
> > > Right, a piggyback-style loader would likely fail in that case.
> >
> > Which is exactly the interesting case for x86_64.  So, since Paul's
> > verified that grub and lilo just put them far apart, maybe bumping up
> > the size is the right thing to do.  Or always putting the initrd at
> > the top of emulated RAM.
> 
> I'd prefer the latter, so that both big and small machines work. Linux still 
> (just about) boots on 8Mb machines.

Like this?  I can't reliably test that it fixes the problem - for some
bizarre reason, I can now load kernels without this patch.  But it
looks right and I can load kernels with it, too.

-- 
Daniel Jacobowitz
CodeSourcery

---
 hw/pc.c |   19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

Index: qemu/hw/pc.c
===================================================================
--- qemu.orig/hw/pc.c	2007-03-31 11:36:34.000000000 -0400
+++ qemu/hw/pc.c	2007-03-31 11:38:24.000000000 -0400
@@ -32,7 +32,6 @@
 #define LINUX_BOOT_FILENAME "linux_boot.bin"
 
 #define KERNEL_LOAD_ADDR     0x00100000
-#define INITRD_LOAD_ADDR     0x00600000
 #define KERNEL_PARAMS_ADDR   0x00090000
 #define KERNEL_CMDLINE_ADDR  0x00099000
 
@@ -452,6 +451,7 @@ static void pc_init1(int ram_size, int v
     char buf[1024];
     int ret, linux_boot, initrd_size, i;
     ram_addr_t ram_addr, vga_ram_addr, bios_offset, vga_bios_offset;
+    ram_addr_t initrd_offset;
     int bios_size, isa_bios_size, vga_bios_size;
     PCIBus *pci_bus;
     int piix3_devfn = -1;
@@ -599,8 +599,21 @@ static void pc_init1(int ram_size, int v
         
         /* load initrd */
         initrd_size = 0;
+        initrd_offset = 0;
         if (initrd_filename) {
-            initrd_size = load_image(initrd_filename, phys_ram_base + INITRD_LOAD_ADDR);
+            initrd_size = get_image_size (initrd_filename);
+            if (initrd_size > 0) {
+                initrd_offset = ram_size - initrd_size;
+                if (initrd_size > ram_size ||
+                    initrd_offset < KERNEL_LOAD_ADDR + ret) {
+                    fprintf(stderr,
+                            "qemu: memory too small for initial ram disk '%s'\n",
+                            initrd_filename);
+                    exit(1);
+                }
+                initrd_size = load_image(initrd_filename,
+                                         phys_ram_base + initrd_offset);
+            }
             if (initrd_size < 0) {
                 fprintf(stderr, "qemu: could not load initial ram disk '%s'\n", 
                         initrd_filename);
@@ -608,7 +621,7 @@ static void pc_init1(int ram_size, int v
             }
         }
         if (initrd_size > 0) {
-            stl_raw(phys_ram_base + KERNEL_PARAMS_ADDR + 0x218, INITRD_LOAD_ADDR);
+            stl_raw(phys_ram_base + KERNEL_PARAMS_ADDR + 0x218, initrd_offset);
             stl_raw(phys_ram_base + KERNEL_PARAMS_ADDR + 0x21c, initrd_size);
         }
         pstrcpy(phys_ram_base + KERNEL_CMDLINE_ADDR, 4096,