[Bug 203699] New: Kernel 5.2-rc1 fails to boot on a Mac Mini G4: dt_headr_start=0x01501000

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https://bugzilla.kernel.org/show_bug.cgi?id=203699

            Bug ID: 203699
           Summary: Kernel 5.2-rc1 fails to boot on a Mac Mini G4:
                    dt_headr_start=0x01501000
           Product: Platform Specific/Hardware
           Version: 2.5
    Kernel Version: Kernel 5.2
          Hardware: PPC-32
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: blocking
          Priority: P1
         Component: PPC-32
          Assignee: platform_ppc-32@kernel-bugs.osdl.org
          Reporter: mathieu.malaterre@gmail.com
        Regression: No

From: Christophe Leroy <>

I found the issue. In order to be able to support KASAN, the setup of 
segments have moved earlier in the boot. Your problem is a side effect 
of this change.
Function setup_disp_bat() is supposed to setup BAT3 for btext data.
But setup_disp_bat() rely on someone setting in disp_BAT the values to 
be loaded into BATs. This is done by btext_prepare_BAT() which is called 
by bootx_init().
The problem is that bootx_init() is never called, so setup_disp_bat() 
does nothing and the access to btext data is possible because the 
bootloader has set an entry for it in the hash table.

But by setting up the segment earlier, we break the bootloader hash 
table, which shouldn't be an issue if the BATs had been set properly as 
expected.

The problematic commit is 215b823707ce ("powerpc/32s: set up an early 
static hash table for KASAN)"

Here is a dirty fix that works for me when CONFIG_KASAN is NOT set.
Of course, the real fix has to be to setup the BATs properly, but I 
won't have time to look at that before June. Maybe you can ?

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