Re: [PATCH 04/10] i386: clean up bzImage generation

H. Peter Anvin wrote:

Jeremy Fitzhardinge wrote:
  

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H. Peter Anvin wrote:
    

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Jeremy Fitzhardinge wrote:
  
      

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-setup_move_size: .word  0x8000		# size to move, when setup is not
+setup_move_size: .word  _setup_size	# size to move, when setup is not
 					# loaded at 0x90000. We will move setup
 					# to 0x90000 then just before jumping
 					# into the kernel. However, only the
    
        

This is WRONG and will break 2.00 protocol bootloaders, if any still
exist, and quite possibly some 2.01 protocol bootloaders.  There are
definitiely bootloaders in the field that rely on this implicit value.   
      

Ah, I see.  I didn't see any documentation saying that this must be
0x8000.  Or does _setup_size just have to be <= 0x8000?

    

The default for unaware bootloaders has been 0x8000 since the boot
protocol was created, and bootloaders are known to (improperly) rely on
it.  _setup_size does have to be <= 0x8000, but that's another issue.
  

Hm, so the worst that could happen is that an old bootloader will
over-copy 0x8000 bytes rather than the specified amount?  How would that
break anything?

I said it probably wouldn't hurt to drop it.  I don't believe you ever
actually explained why you wanted it dropped.

Well, I don't specifically care for Xen; I don't really mind either way
in general.  I'll break it into a separate patch and we can handle it
that way.

    J