2022-01-21 22:21:39

by Myrtle Shah

Subject: [PATCH 0/2] riscv: Fixes for XIP support

Apologies for the spam, resending as this appeared to break
the first time.

These are some initial patches to bugs I found attempting to
get a XIP kernel working on hardware:
- 32-bit VexRiscv processor
- kernel in SPI flash, at 0x00200000
- 16MB of RAM at 0x10000000
- MMU enabled

The system isn't actually booting yet; but at least the
initial memory management setup completes with these
patches as opposed to crashing almost straight away.

2022-01-21 22:21:42

by Myrtle Shah

Subject: [PATCH 2/2] riscv/mm: Add some missing XIP_FIXUPs

Signed-off-by: Myrtle Shah <[email protected]>
---
arch/riscv/mm/init.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 0624c68331d8..eeafefd1c2b3 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -41,6 +41,7 @@ phys_addr_t phys_ram_base __ro_after_init;
EXPORT_SYMBOL(phys_ram_base);

#ifdef CONFIG_XIP_KERNEL
+#define phys_ram_base (*(phys_addr_t *)XIP_FIXUP(&phys_ram_base))
extern char _xiprom[], _exiprom[], __data_loc;
#endif

@@ -248,6 +249,7 @@ pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
static pmd_t __maybe_unused early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);

#ifdef CONFIG_XIP_KERNEL
+#define riscv_pfn_base (*(unsigned long *)XIP_FIXUP(&riscv_pfn_base))
#define trampoline_pg_dir ((pgd_t *)XIP_FIXUP(trampoline_pg_dir))
#define fixmap_pte ((pte_t *)XIP_FIXUP(fixmap_pte))
#define early_pg_dir ((pgd_t *)XIP_FIXUP(early_pg_dir))
--
2.34.1