On Tue, Jun 17, 2008 at 5:31 AM, Robert Millan <[EMAIL PROTECTED]> wrote:
> On Mon, Jun 16, 2008 at 08:37:43PM +0800, Bean wrote:
>>
>> But do we really need those space ?
>
> The typical use case where space is a PITA is boot an LVM system without a
> separate /boot partition. There we don't have the ressort of using a
> blocklist (which is already bad), so embedding core.img is mandatory, but
> at the same time, we have to load lvm.mod in (possibly raid.mod as well),
> and then you see where I'm going...
>
> For example, with current CVS:
>
> $ ./grub-mkimage -d . biosdisk pc ext2 lvm -o /tmp/core.img && du -b
> /tmp/core.img
> 30511 /tmp/core.img
>
> $ ./grub-mkimage -d . biosdisk pc ext2 lvm raid -o /tmp/core.img && du -b
> /tmp/core.img
> 32940 /tmp/core.img
>
> The first is close to the limit (32256 B) and the second surpasses it, so
> boot from LVM on RAID with DOS label and ext2 is a use case we can't support
> right now.
I run some tests on the your situation:
Current CVS:
/grub-mkimage -d . biosdisk pc ext2 lvm raid -o c1.img && du -b c1.img
32735 c1.img
Then I comment out the lzo compression in grub-mkimage with this patch:
diff --git a/util/i386/pc/grub-mkimage.c b/util/i386/pc/grub-mkimage.c
index 189ec4e..cb069ec 100644
--- a/util/i386/pc/grub-mkimage.c
+++ b/util/i386/pc/grub-mkimage.c
@@ -59,9 +59,11 @@ compress_kernel (char *kernel_img, size_t kernel_size,
*core_img = xmalloc (kernel_size + kernel_size / 64 + 16 + 3);
wrkmem = xmalloc (LZO1X_999_MEM_COMPRESS);
- memcpy (*core_img, kernel_img, GRUB_KERNEL_MACHINE_RAW_SIZE);
+ //memcpy (*core_img, kernel_img, GRUB_KERNEL_MACHINE_RAW_SIZE);
+ memcpy (*core_img, kernel_img, kernel_size);
grub_util_info ("compressing the core image");
+/*
if (lzo1x_999_compress ((const lzo_byte *) (kernel_img
+ GRUB_KERNEL_MACHINE_RAW_SIZE),
kernel_size - GRUB_KERNEL_MACHINE_RAW_SIZE,
@@ -70,10 +72,12 @@ compress_kernel (char *kernel_img, size_t kernel_size,
&size, wrkmem)
!= LZO_E_OK)
grub_util_error ("cannot compress the kernel image");
-
+*/
free (wrkmem);
- *core_size = (size_t) size + GRUB_KERNEL_MACHINE_RAW_SIZE;
+ //*core_size = (size_t) size + GRUB_KERNEL_MACHINE_RAW_SIZE;
+
+ *core_size = kernel_size;
}
static void
/grub-mkimage -d . biosdisk pc ext2 lvm raid -o c2.img && du -b c2.img
55572 c2.img
Finally, I use lzma to compress it:
lzma c2.img && du -b c2.img.lzma
26737 c2.img.lzma
The decompresser is about 2K, we should also exclude the uncompressed
part at the beginning of kernel, but there is still plenty room left.
>
>> I think lzo is working fine, we
>> should avoid switching unless there is a good reason to do so.
>
> ISTR Okuji didn't like it; can't remember why.
He is concerned about compression ratio, but doesn't mind in the end:
http://lists.gnu.org/archive/html/grub-devel/2007-12/msg00120.html
--
Bean
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