Re: Compressed kernels currently won't boot

[Helge Deller <deller@gmx.de>]

[-- Attachment #1: Type: text/plain, Size: 1517 bytes --]

On 31.07.19 23:13, Helge Deller wrote:
> On 31.07.19 23:08, Sven Schnelle wrote:
>> Hi,
>>
>> On Wed, Jul 31, 2019 at 02:01:34PM -0700, James Bottomley wrote:
>>> On Wed, 2019-07-31 at 21:44 +0200, Sven Schnelle wrote:
>>>> Hi James,
>>>>
>>>> On Wed, Jul 31, 2019 at 12:40:12PM -0700, James Bottomley wrote:
>>>>
>>>>> What about causing the compressed make to build both a stripped and
>>>>> a non-stripped bzImage (say sbzImage and bzImage).  That way you
>>>>> always have the stripped one available for small size things like
>>>>> boot from tape or DVD?  but in the usual case we use the bzImage
>>>>> with full contents.
>>>>
>>>> In that case we would also need to build two lifimages - how about
>>>> adding a config option option? Something like "Strip debug
>>>> information from compressed kernel images"?
>>>
>>> Actually, I just looked at what x86 does.  It has this in the
>>> arch/x86/boot/compressed/Makefile:
>>>
>>> OBJCOPYFLAGS_vmlinux.bin :=  -R .comment -S
>>> $(obj)/vmlinux.bin: vmlinux FORCE
>>>     $(call if_changed,objcopy)
>>>
>>> So it basically strips all the debug information from the kernel before
>>> compressing, which argues there's no need to retain the information
>>> because x86 doesn't bother.
>>
>> Nice. So we could convince Helge by saying "Look, x86 is also stripping it"! :-)
>
> I'm fine with doing exactly why x86 does :-)

Attached is the revised patch, and it gets the compressed kernel down
from 32MB to 3.8MB.

Helge

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: drop-debug.patch --]
[-- Type: text/x-patch; name="drop-debug.patch", Size: 1220 bytes --]

diff --git a/arch/parisc/boot/compressed/Makefile b/arch/parisc/boot/compressed/Makefile
index 2da8624e5cf6..c54d9d0f6043 100644
--- a/arch/parisc/boot/compressed/Makefile
+++ b/arch/parisc/boot/compressed/Makefile
@@ -55,7 +55,8 @@ $(obj)/misc.o: $(obj)/sizes.h
 CPPFLAGS_vmlinux.lds += -I$(objtree)/$(obj) -DBOOTLOADER
 $(obj)/vmlinux.lds: $(obj)/sizes.h

-$(obj)/vmlinux.bin: vmlinux
+OBJCOPYFLAGS_vmlinux.bin :=  -R .comment -S
+$(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)

 vmlinux.bin.all-y := $(obj)/vmlinux.bin
diff --git a/arch/parisc/boot/compressed/vmlinux.lds.S b/arch/parisc/boot/compressed/vmlinux.lds.S
index bfd7872739a3..2ac3a643f2eb 100644
--- a/arch/parisc/boot/compressed/vmlinux.lds.S
+++ b/arch/parisc/boot/compressed/vmlinux.lds.S
@@ -48,8 +48,8 @@ SECTIONS
 		*(.rodata.compressed)
 	}

-	/* bootloader code and data starts behind area of extracted kernel */
-	. = (SZ_end - SZparisc_kernel_start + KERNEL_BINARY_TEXT_START);
+	/* bootloader code and data starts at least behind area of extracted kernel */
+	. = MAX(ABSOLUTE(.), (SZ_end - SZparisc_kernel_start + KERNEL_BINARY_TEXT_START));

 	/* align on next page boundary */
 	. = ALIGN(4096);