Currently, if boot with extlinux.conf and do not set the fdt U-Boot will provide its own device tree. This behavior is beneficial if the U-Boot device tree is in sync with Linux, but it totally halts the booting of pre-dtb kernels (3.4 for example) since it uses ATAGs. To fix this, pass `-` in the fdt extlinux field as a signal that no tree should be used.
Suggested-by: Jonas Schwöbel jonasschwoebel@yahoo.de Tested-by: Jethro Bull jethrob@hotmail.com Signed-off-by: Svyatoslav Ryhel clamor95@gmail.com --- boot/pxe_utils.c | 8 +++++--- doc/develop/distro.rst | 3 +++ 2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/boot/pxe_utils.c b/boot/pxe_utils.c index 83bc167785..6a2c881965 100644 --- a/boot/pxe_utils.c +++ b/boot/pxe_utils.c @@ -634,7 +634,8 @@ static int label_boot(struct pxe_context *ctx, struct pxe_label *label) char *fdtfilefree = NULL;
if (label->fdt) { - fdtfile = label->fdt; + if (strcmp("-", label->fdt)) + fdtfile = label->fdt; } else if (label->fdtdir) { char *f1, *f2, *f3, *f4, *slash;
@@ -731,13 +732,14 @@ static int label_boot(struct pxe_context *ctx, struct pxe_label *label) zboot_argc = 5; }
- if (!bootm_argv[3]) + if (!bootm_argv[3] && strcmp("-", label->fdt)) bootm_argv[3] = env_get("fdt_addr");
kernel_addr_r = genimg_get_kernel_addr(kernel_addr); buf = map_sysmem(kernel_addr_r, 0);
- if (!bootm_argv[3] && genimg_get_format(buf) != IMAGE_FORMAT_FIT) + if (!bootm_argv[3] && genimg_get_format(buf) != IMAGE_FORMAT_FIT && + strcmp("-", label->fdt)) bootm_argv[3] = env_get("fdtcontroladdr");
if (bootm_argv[3]) { diff --git a/doc/develop/distro.rst b/doc/develop/distro.rst index 8016acad09..c81da8a0fd 100644 --- a/doc/develop/distro.rst +++ b/doc/develop/distro.rst @@ -81,6 +81,9 @@ as specified at `Boot Loader Specification`_: * Does not document the fdtdir option, which automatically selects the DTB to pass to the kernel.
+* If no fdt/fdtdir is provided, the U-Boot will pass its own device tree, and + if fdt is passed with ``-``, then device tree will not be used (legacy booting). + See also doc/README.pxe under 'pxe file format'.
One example extlinux.conf generated by the Fedora installer is::