Because the BTX mini-kernel now uses flat memory mode and clients

are no longer limited to a virtual address space of 16 megabytes,
only mask high two bits of a virtual address.  This allows to load
larger kernels (up to 1 gigabyte).  Not masking addresses at all
was a bad idea on machines with less than >3G of memory -- kernels
are linked at 0xc0xxxxxx, and that would attempt to load a kernel
at above 3G.  By masking only two highest bits we stay within the
safe limits while still allowing to boot larger kernels.

(This is a safer reimplmentation of sys/boot/i386/boot2/boot.2.c
rev. 1.71.)

Prodded by:	jhb
Tested by:	nyan (pc98)

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/boot/i386/gptboot/gptboot.c b/sys/boot/i386/gptboot/gptboot.c
index df3fe81..b07c9ed 100644
--- a/sys/boot/i386/gptboot/gptboot.c
+++ b/sys/boot/i386/gptboot/gptboot.c
@@ -334,7 +334,7 @@ load(void)
 	return;
     }
     if (fmt == 0) {
-	addr = hdr.ex.a_entry & 0xffffff;
+	addr = hdr.ex.a_entry & 0x3fffffff;
 	p = PTOV(addr);
 	fs_off = PAGE_SIZE;
 	if (xfsread(ino, p, hdr.ex.a_text))
@@ -368,7 +368,7 @@ load(void)
 		j++;
 	}
 	for (i = 0; i < 2; i++) {
-	    p = PTOV(ep[i].p_paddr & 0xffffff);
+	    p = PTOV(ep[i].p_paddr & 0x3fffffff);
 	    fs_off = ep[i].p_offset;
 	    if (xfsread(ino, p, ep[i].p_filesz))
 		return;
@@ -389,7 +389,7 @@ load(void)
 		p += es[i].sh_size;
 	    }
 	}
-	addr = hdr.eh.e_entry & 0xffffff;
+	addr = hdr.eh.e_entry & 0x3fffffff;
     }
     bootinfo.bi_esymtab = VTOP(p);
     bootinfo.bi_kernelname = VTOP(kname);