From: Christophe Leroy christophe.leroy@csgroup.eu
Since Linux v6.7, booting using BootX on an Old World PowerMac produces an early crash. Stan Johnson writes, "the symptoms are that the screen goes blank and the backlight stays on, and the system freezes (Linux doesn't boot)." Further testing revealed that the failure can be avoided by disabling CONFIG_BOOTX_TEXT. Bisection revealed that the regression was caused by a patch which replaced the static btext font data with const data in a different compilation unit. To fix this, access the font data at its relocated address.
Cc: Cedar Maxwell cedarmaxwell@mac.com Cc: Stan Johnson userm57@yahoo.com Cc: "Dr. David Alan Gilbert" linux@treblig.org Cc: Benjamin Herrenschmidt benh@kernel.crashing.org Cc: stable@vger.kernel.org Link: https://lists.debian.org/debian-powerpc/2025/10/msg00111.html Link: https://lore.kernel.org/linuxppc-dev/d81ddca8-c5ee-d583-d579-02b19ed95301@ya... Reported-by: Cedar Maxwell cedarmaxwell@mac.com Closes: https://lists.debian.org/debian-powerpc/2025/09/msg00031.html Bisected-by: Stan Johnson userm57@yahoo.com Tested-by: Stan Johnson userm57@yahoo.com Fixes: 0ebc7feae79a ("powerpc: Use shared font data") Signed-off-by: Finn Thain fthain@linux-m68k.org
---
Christophe, as you're the author of this patch, this submission will probably need your sign-off.
--- arch/powerpc/kernel/btext.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/btext.c b/arch/powerpc/kernel/btext.c index 7f63f1cdc6c3..ca00c4824e31 100644 --- a/arch/powerpc/kernel/btext.c +++ b/arch/powerpc/kernel/btext.c @@ -20,6 +20,7 @@ #include <asm/io.h> #include <asm/processor.h> #include <asm/udbg.h> +#include <asm/setup.h>
#define NO_SCROLL
@@ -463,7 +464,7 @@ static noinline void draw_byte(unsigned char c, long locX, long locY) { unsigned char *base = calc_base(locX << 3, locY << 4); unsigned int font_index = c * 16; - const unsigned char *font = font_sun_8x16.data + font_index; + const unsigned char *font = PTRRELOC(font_sun_8x16.data) + font_index; int rb = dispDeviceRowBytes;
rmci_maybe_on();