On Mon, 1 Apr 2019 at 03:46, Eugeniu Rosca erosca@de.adit-jv.com wrote:
The 'no_fdt' goto label was introduced by v2015.01 commit [0] and it had two review stages [1-2]. The *documented* purpose behind commit [0] is (excerpt from commit description):
allows both FDT and non-FDT kernels to boot by making the third parameter to the bootm/bootz optional
While [1] and [2] share the same goal, they have very different implementations:
- [1] was based on a very simple 'argc' check at function error out with returning success to the caller if the third parameter was NOT passed to bootm/bootz command. This approach had the downside of returning success to the caller even in case of legitimate internal errors, which should halt booting.
- [2] added the "no_fdt" label and several "goto no_fdt" statements. This allowed to report the legitimate internal errors to the caller.
IOW the major difference between [1] and [2] is:
- [1] boot w/o FDT if FDT address is not passed to boot{m,z,*}
- [2] give *freedom* to the developer to boot w/o FDT from any (more or less) arbitrary point in the function flow (and here comes the peculiar aspect, which looks to be a leftover from [1]) with the precondition that the 3rd argument (FDT address) is NOT provided to boot{m,z,*}. In practice, this means that only a subset of "goto no_fdt" end up booting w/o FDT while the other subset is returning an error to the caller.
This patch removes the peculiar behavior described above, such that "goto no_fdt" performs really what it tells to the developer.
The motivation of this patch is to decrease the unneeded complexity and increase the readability of boot_get_fdt().
[0] 48aead71c1ad ("fdt: Allow non-FDT kernels to boot when CONFIG_OF_LIBFDT is defined") [1] https://patchwork.ozlabs.org/patch/412923/ ("[U-Boot,v1] fdt: Allow non-FDT kernels to boot when CONFIG_OF_LIBFDT is defined") [2] https://patchwork.ozlabs.org/patch/415635/ ("[U-Boot,v2] fdt: Allow non-FDT kernels to boot when CONFIG_OF_LIBFDT is defined")
Signed-off-by: Eugeniu Rosca erosca@de.adit-jv.com
Changes in v2:
- NA
- Link v1: https://patchwork.ozlabs.org/patch/1071587/
common/image-fdt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Simon Glass sjg@chromium.org
Can we create a test of the boot_get_fdt() behaviour?
We have test_fit and test_vboot as possible examples, although perhaps a test that directly calls this function would be better?
Regards, Simon
diff --git a/common/image-fdt.c b/common/image-fdt.c index 1817ce6bce30..c335e7e2f220 100644 --- a/common/image-fdt.c +++ b/common/image-fdt.c @@ -489,7 +489,7 @@ int boot_get_fdt(int flag, int argc, char * const argv[], uint8_t arch, no_fdt: ok_no_fdt = 1; error:
if (!select && ok_no_fdt) {
if (ok_no_fdt) { debug("Continuing to boot without FDT\n"); return 0; }-- 2.21.0