The page previously selected for the AP boot code is actually still in
use by the ELF section headers table. That this page is marked as
temporary boot data prevented an assertion but did mean that the ELF
page was overwritten. The assertion shows up when booting with
multiboot2. A genuinely free page with as low a physical address as
possible is now selected instead.
---
i386/i386at/biosmem.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/i386/i386at/biosmem.c b/i386/i386at/biosmem.c
index 6c659044..5c788705 100644
--- a/i386/i386at/biosmem.c
+++ b/i386/i386at/biosmem.c
@@ -690,12 +690,17 @@ biosmem_bootstrap_common(void)
boot_panic(biosmem_panic_noseg_msg);
#if !defined(MACH_HYP) && NCPUS > 1
+ phys_addr_t avail_start, avail_end;
/*
* Grab an early page for AP boot code which needs to be below 1MB.
*/
- assert (phys_start < 0x100000);
- apboot_addr = phys_start;
- phys_start += PAGE_SIZE;
+ if (biosmem_find_avail(phys_start, phys_end, &avail_start, &avail_end)
+ || ((avail_end - avail_start) < PAGE_SIZE)
+ || (avail_start >= 0x100000))
+ panic("No memory for AP boot code.\n");
+
+ apboot_addr = avail_start;
+ biosmem_register_boot_data(apboot_addr, apboot_addr + PAGE_SIZE, FALSE);
#endif
biosmem_set_segment(VM_PAGE_SEG_DMA, phys_start, phys_end);
--
2.47.3
