summaryrefslogtreecommitdiffstats
path: root/kernel/arch/cris/boot/compressed/README
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/arch/cris/boot/compressed/README')
-rw-r--r--kernel/arch/cris/boot/compressed/README24
1 files changed, 24 insertions, 0 deletions
diff --git a/kernel/arch/cris/boot/compressed/README b/kernel/arch/cris/boot/compressed/README
new file mode 100644
index 000000000..182c5d757
--- /dev/null
+++ b/kernel/arch/cris/boot/compressed/README
@@ -0,0 +1,24 @@
+Creation of the self-extracting compressed kernel image (vmlinuz)
+-----------------------------------------------------------------
+
+This can be slightly confusing because it's a process with many steps.
+
+The kernel object built by the arch/etrax100/Makefile, vmlinux, is split
+by that makefile into text and data binary files, vmlinux.text and
+vmlinux.data.
+
+Those files together with a ROM filesystem can be catted together and
+burned into a flash or executed directly at the DRAM origin.
+
+They can also be catted together and compressed with gzip, which is what
+happens in this makefile. Together they make up piggy.img.
+
+The decompressor is built into the file decompress.o. It is turned into
+the binary file decompress.bin, which is catted together with piggy.img
+into the file vmlinuz. It can be executed in an arbitrary place in flash.
+
+Be careful - it assumes some things about free locations in DRAM. It
+assumes the DRAM starts at 0x40000000 and that it is at least 8 MB,
+so it puts its code at 0x40700000, and initial stack at 0x40800000.
+
+-Bjorn