Re: [PATCH v3 11/12] x86, boot: add fields to support load bzImageand ramdisk high
From: H. Peter Anvin
Date: Wed Nov 21 2012 - 12:17:39 EST
On 11/20/2012 11:16 PM, Yinghai Lu wrote:
diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index 9efceff..a8263f7 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -57,6 +57,9 @@ Protocol 2.10: (Kernel 2.6.31) Added a protocol for relaxed alignment
Protocol 2.11: (Kernel 3.6) Added a field for offset of EFI handover
protocol entry point.
+Protocol 2.12: (Kernel 3.9) Added three fields for loading bzImage and
+ ramdisk above 4G with 64bit.
+
**** MEMORY LAYOUT
The traditional memory map for the kernel loader, used for Image or
@@ -182,7 +185,7 @@ Offset Proto Name Meaning
0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel
0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not
0235/1 2.10+ min_alignment Minimum alignment, as a power of two
-0236/2 N/A pad3 Unused
+0236/2 2.12+ xloadflags Boot protocal option flags
^^^^^^^^
0238/4 2.06+ cmdline_size Maximum size of the kernel command line
023C/4 2.07+ hardware_subarch Hardware subarchitecture
0240/8 2.07+ hardware_subarch_data Subarchitecture-specific data
@@ -193,6 +196,9 @@ Offset Proto Name Meaning
0258/8 2.10+ pref_address Preferred loading address
0260/4 2.10+ init_size Linear memory required during initialization
0264/4 2.11+ handover_offset Offset of handover entry point
+0268/4 2.12+ ext_ramdisk_image ramdisk_image 32 bits
"high 32 bits" presumably...
+026C/4 2.12+ ext_ramdisk_size ramdisk_size high 32 bits
+0270/4 2.12+ ext_cmd_line_ptr cmd_line_ptr high 32 bits
I'm looking at these three fields and I'm getting worried about space --
there are only two more word-sized fields possible in this structure.
Since these fields are not initialized (default to zero) and almost
certainly aren't useful for people entering via the 16-bit entry point I
think we should move them out of struct setup_header and into the
remainder of struct boot_param.
diff --git a/arch/x86/boot/compressed/cmdline.c b/arch/x86/boot/compressed/cmdline.c
index b4c913c..00678d3 100644
--- a/arch/x86/boot/compressed/cmdline.c
+++ b/arch/x86/boot/compressed/cmdline.c
@@ -17,6 +17,9 @@ static unsigned long get_cmd_line_ptr(void)
{
unsigned long cmd_line_ptr = real_mode->hdr.cmd_line_ptr;
+ if (real_mode->hdr.version >= 0x020c)
+ cmd_line_ptr |= (u64)real_mode->hdr.ext_cmd_line_ptr << 32;
+
return cmd_line_ptr;
}
No. hdr.version is information from the kernel to the bootloader; it is
meaningless to look at it inside the kernel.
Same in a bunch of other places.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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