diff options
Diffstat (limited to 'Documentation/lguest/lguest.c')
| -rw-r--r-- | Documentation/lguest/lguest.c | 42 |
1 files changed, 13 insertions, 29 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index cbf4bec..004c5c6 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -251,23 +251,6 @@ static void *get_pages(unsigned int num) return addr; } -/* To find out where to start we look for the magic Guest string, which marks - * the code we see in lguest_asm.S. This is a hack which we are currently - * plotting to replace with the normal Linux entry point. */ -static unsigned long entry_point(const void *start, const void *end) -{ - const void *p; - - /* The scan gives us the physical starting address. We boot with - * pagetables set up with virtual and physical the same, so that's - * OK. */ - for (p = start; p < end; p++) - if (memcmp(p, "GenuineLguest", strlen("GenuineLguest")) == 0) - return to_guest_phys(p + strlen("GenuineLguest")); - - errx(1, "Is this image a genuine lguest?"); -} - /* This routine is used to load the kernel or initrd. It tries mmap, but if * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries), * it falls back to reading the memory in. */ @@ -303,7 +286,6 @@ static void map_at(int fd, void *addr, unsigned long offset, unsigned long len) * We return the starting address. */ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) { - void *start = (void *)-1, *end = NULL; Elf32_Phdr phdr[ehdr->e_phnum]; unsigned int i; @@ -335,19 +317,13 @@ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) verbose("Section %i: size %i addr %p\n", i, phdr[i].p_memsz, (void *)phdr[i].p_paddr); - /* We track the first and last address we mapped, so we can - * tell entry_point() where to scan. */ - if (from_guest_phys(phdr[i].p_paddr) < start) - start = from_guest_phys(phdr[i].p_paddr); - if (from_guest_phys(phdr[i].p_paddr) + phdr[i].p_filesz > end) - end=from_guest_phys(phdr[i].p_paddr)+phdr[i].p_filesz; - /* We map this section of the file at its physical address. */ map_at(elf_fd, from_guest_phys(phdr[i].p_paddr), phdr[i].p_offset, phdr[i].p_filesz); } - return entry_point(start, end); + /* The entry point is given in the ELF header. */ + return ehdr->e_entry; } /*L:160 Unfortunately the entire ELF image isn't compressed: the segments @@ -374,7 +350,8 @@ static unsigned long unpack_bzimage(int fd) verbose("Unpacked size %i addr %p\n", len, img); - return entry_point(img, img + len); + /* The entry point for a bzImage is always the first byte */ + return (unsigned long)img; } /*L:150 A bzImage, unlike an ELF file, is not meant to be loaded. You're @@ -1684,8 +1661,15 @@ int main(int argc, char *argv[]) *(u32 *)(boot + 0x228) = 4096; concat(boot + 4096, argv+optind+2); - /* The guest type value of "1" tells the Guest it's under lguest. */ - *(int *)(boot + 0x23c) = 1; + /* Boot protocol version: 2.07 supports the fields for lguest. */ + *(u16 *)(boot + 0x206) = 0x207; + + /* The hardware_subarch value of "1" tells the Guest it's an lguest. */ + *(u32 *)(boot + 0x23c) = 1; + + /* Set bit 6 of the loadflags (aka. KEEP_SEGMENTS) so the entry path + * does not try to reload segment registers. */ + *(u8 *)(boot + 0x211) |= (1 << 6); /* We tell the kernel to initialize the Guest: this returns the open * /dev/lguest file descriptor. */ |