Re: [RFC] arm64: early_ioremap fails to map ACPI MADT on 64K pages

From: Yu Peng

Date: Mon Jun 22 2026 - 22:47:33 EST


Hi Lorenzo, Hanjun, Will,

Thanks for confirming.

I will send a proper patch for this. The change I plan to post is along
these lines:

diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h
index ... .. ...
--- a/arch/arm64/include/asm/fixmap.h
+++ b/arch/arm64/include/asm/fixmap.h
@@ -79,7 +79,11 @@ enum fixed_addresses {
* Temporary boot-time mappings, used by early_ioremap(),
* before ioremap() is functional.
*/
+#ifdef CONFIG_ARM64_64K_PAGES
+#define NR_FIX_BTMAPS (SZ_512K / PAGE_SIZE)
+#else
#define NR_FIX_BTMAPS (SZ_256K / PAGE_SIZE)
+#endif
#define FIX_BTMAPS_SLOTS 7
#define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)

Thanks,
Yu Peng