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authorJosh Triplett <josh@joshtriplett.org>2013-03-27 14:50:37 -0700
committerMatt Fleming <matt.fleming@intel.com>2013-04-08 08:41:38 +0100
commitf16d2c170888fb416a7b376eb0a29dd3f7cced24 (patch)
tree243e7666eb1055d2ce9999a42c3f890e983699eb /com32
parent66d551acdb0d516f43702983184483687c2128e4 (diff)
downloadsyslinux-f16d2c170888fb416a7b376eb0a29dd3f7cced24.tar.gz
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Fix support for Linux kernel images with no protected mode code
Some kernel images use the Linux kernel boot protocol and header structure, but do not actually have any protected-mode code. For instance, grub's 1024-byte lnxboot.img consists of 1024 real-mode bytes and 0 protected-mode bytes; you can concatenate it with a full grub core.img to produce a self-contained bootable kernel, but you can also use it standalone as the kernel with the core.img loaded as an initrd. syslinux 4 supports this, but it no longer works with syslinux 5: the memmap functions do not correctly handle a request to work with a 0-byte region. With lnxboot.img, this would cause syslinux to bail because it thinks it has no space at the 1M load location but cannot relocate lnxboot.img. (In bailing, it gives the confusing error message "Bad file descriptor", not because that error actually occurred when attempting to boot the kernel, but because errno has that value on entry to syslinux_boot_linux and nothing clears or sets it.) Fix the regression by handling the corner case of no protected-mode code explicitly. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Burt Triplett <burt@pbjtriplett.org> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Diffstat (limited to 'com32')
-rw-r--r--com32/lib/syslinux/load_linux.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/com32/lib/syslinux/load_linux.c b/com32/lib/syslinux/load_linux.c
index 471d8a50..04a52107 100644
--- a/com32/lib/syslinux/load_linux.c
+++ b/com32/lib/syslinux/load_linux.c
@@ -324,7 +324,8 @@ int syslinux_boot_linux(void *kernel_buf, size_t kernel_size,
/* Place the kernel in memory */
/* First, find a suitable place for the protected-mode code */
- if (syslinux_memmap_type(amap, prot_mode_base, prot_mode_size)
+ if (prot_mode_size &&
+ syslinux_memmap_type(amap, prot_mode_base, prot_mode_size)
!= SMT_FREE) {
const struct syslinux_memmap *mp;
if (!hdr.relocatable_kernel)
@@ -423,12 +424,15 @@ int syslinux_boot_linux(void *kernel_buf, size_t kernel_size,
}
/* Protected-mode code */
- if (syslinux_add_movelist(&fraglist, prot_mode_base,
- (addr_t) kernel_buf + real_mode_size,
- prot_mode_size))
- goto bail;
- if (syslinux_add_memmap(&amap, prot_mode_base, prot_mode_size, SMT_ALLOC))
- goto bail;
+ if (prot_mode_size) {
+ if (syslinux_add_movelist(&fraglist, prot_mode_base,
+ (addr_t) kernel_buf + real_mode_size,
+ prot_mode_size))
+ goto bail;
+ if (syslinux_add_memmap(&amap, prot_mode_base, prot_mode_size,
+ SMT_ALLOC))
+ goto bail;
+ }
/* Figure out the size of the initramfs, and where to put it.
We should put it at the highest possible address which is