linux-kernel - Re: [PATCH v4] powerpc: Use shared font data

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Message-ID: <3017c67c-87e9-c06f-3146-ee461cd6603f@yahoo.com>
Date: Tue, 4 Nov 2025 12:49:08 -0700
From: Stan Johnson <userm57@...oo.com>
To: "Dr. David Alan Gilbert" <linux@...blig.org>
Cc: mpe@...erman.id.au, npiggin@...il.com, christophe.leroy@...roup.eu,
 sam@...nborg.org, benh@...nel.crashing.org, linuxppc-dev@...ts.ozlabs.org,
 linux-kernel@...r.kernel.org, rdunlap@...radead.org,
 Cedar Maxwell <cedarmaxwell@....com>, Finn Thain <fthain@...ux-m68k.org>
Subject: Re: [PATCH v4] powerpc: Use shared font data

Please see the attached config file that Finn sent to me along with his 
patch. The relevant line is "CONFIG_BOOTX_TEXT=y"; without that, the 
kernel boots on the Wallstreet.

On 11/4/25 10:59 AM, Dr. David Alan Gilbert wrote:
> * Finn Thain (fthain@...ux-m68k.org) wrote:
>>
>> On Mon, 3 Nov 2025, Dr. David Alan Gilbert wrote:
>>
>>>
>>>> Anyway, I imagine that the problem with your patch was that it relies
>>>> on font data from a different (read only) section, which is
>>>> unavailable for some reason (MMU not fully configured yet?)
>>>>
>>>> So I've asked Stan to test a patch that simply removes the relevant
>>>> 'const' keywords. It's not a solution, but might narrow-down the
>>>> search.
>>>
>>
>> Stan tested my patch to remove 'const' from the font_desc and font_data
>> structs but it did not help. (There goes that theory.)
>>
>>> I wonder if this is a compiler-flag-ism;  I see
>>> arch/powerpc/kernel/Makefile has a pile of special flags, and for
>>> btext.o it has a -fPIC (as well as turning off some other flags). I
>>> wonder if bodging those in lib/fonts/Makefile for
>>> lib/fonts/font_sun8x16.c fixes it? But... this is data - there's no code
>>> is there - are any of those flags relevant for data only?
>>>
>>
>> I don't know. But I'm sure Stan would be willing to test a patch for you.
> 
> Can one of you point me at the config you're testing with so I can
> try some builds with it.
> 
> Dave
> 
>>>>
>>>> The BootX bootloader doesn't work on New World systems, which is
>>>> probably why we don't see this regression on anything newer than a
>>>> Wallstreet.
>>>>
>>>> It's likely that other Old World systems are also affected, if they
>>>> are using BootX. We don't yet know whether the regression also affects
>>>> Old World systems using the iQUIK bootloader instead of BootX.
>>>
>>> OK, remember I don't think I've ever tried PPC via MacOS booting, so not
>>> familiar with it.
>>>
>>
>> I will try to set up a MacOS guest in QEMU, to see if the hang can be
>> reproduced that way.
>>
Download attachment "dot-config-powermac-6.17.xz" of type "application/x-xz" (19936 bytes)