[U-Boot-Users] [PATCH v2] [new uImage] ppc: Re-order ramdisk/fdt handling sequence

Jerry Van Baren
2008-02-18T19:15:53Z

Kumar Gala wrote:
>
> On Feb 18, 2008, at 11:51 AM, Jerry Van Baren wrote:
>
>> Kumar Gala wrote:
>>> Doing the fdt before the ramdisk allows us to grow the fdt w/o concern
>>> however it does mean we have to go in and fixup the initrd info since
>>> we don't know where it will be.
>>> Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
>>
>> Hi Kumar,
>>
>>> ---
>>> Fixed up the error handling. The old code tried returning an error and
>>> should have called do_reset().
>>> lib_ppc/bootm.c | 40 +++++++++++++++++++++++++++++++++++-----
>>> 1 files changed, 35 insertions(+), 5 deletions(-)
>>> diff --git a/lib_ppc/bootm.c b/lib_ppc/bootm.c
>>> index 5158ccc..09e349e 100644
>>> --- a/lib_ppc/bootm.c
>>> +++ b/lib_ppc/bootm.c
>>> @@ -71,7 +71,7 @@ do_bootm_linux(cmd_tbl_t *cmdtp, int flag,
>>> bd_t *kbd;
>>> void (*kernel)(bd_t *, ulong, ulong, ulong, ulong);
>>> - int has_of = 0;
>>> + int ret, has_of = 0;
>>
>> I would strongly prefer to see "ret" declared on a separate line. I'm
>> not a fan of comma declared variables and, when one is initialized and
>> the other isn't, it makes my brain play tricks on me (thinking ret is
>> initialized to 0 too, which it isn't).
>>
>>> #if defined(CONFIG_OF_LIBFDT)
>>> char *of_flat_tree;
>>> @@ -121,9 +121,6 @@ do_bootm_linux(cmd_tbl_t *cmdtp, int flag,
>>> rd_len = rd_data_end - rd_data_start;
>>> - alloc_current = ramdisk_high (alloc_current, rd_data_start, rd_len,
>>> - sp_limit, get_sp (), &initrd_start, &initrd_end);
>>> -
>>> #if defined(CONFIG_OF_LIBFDT)
>>> /* find flattened device tree */
>>> alloc_current = get_fdt (alloc_current,
>>> @@ -134,7 +131,8 @@ do_bootm_linux(cmd_tbl_t *cmdtp, int flag,
>>> * if the user wants it (the logic is in the subroutines).
>>> */
>>> if (of_flat_tree) {
>>> - if (fdt_chosen(of_flat_tree, initrd_start, initrd_end, 0) <
>>> 0) {
>>> + /* pass in dummy initrd info, we'll fix up later */
>>> + if (fdt_chosen(of_flat_tree, rd_data_start, rd_data_end, 0)
>>> < 0) {
>>
>> If you pass in 0,0 for rd_data_start, rd_data_end it will not create
>> the ramdisk entry...
>
> If rd_data_start, rd_data_end are 0,0 than we don't have a ramdisk, so
> its ok.

My point is to pass in 0,0 *so that* they are not created at all, rather
than passing in dummy values, creating entries that we have to
delete/rewrite later.

>>> fdt_error ("/chosen node create failed");
>>> do_reset (cmdtp, flag, argc, argv);
>>> }
>>> @@ -157,6 +155,38 @@ do_bootm_linux(cmd_tbl_t *cmdtp, int flag,
>>> }
>>> #endif /* CONFIG_OF_LIBFDT */
>>> + alloc_current = ramdisk_high (alloc_current, rd_data_start, rd_len,
>>> + sp_limit, get_sp (), &initrd_start, &initrd_end);
>>> +
>>> +#if defined(CONFIG_OF_LIBFDT)
>>> + /* fixup the initrd now that we know where it should be */
>>> + if ((of_flat_tree) && (initrd_start && initrd_end)) {
>>> + uint64_t addr, size;
>>> + int total = fdt_num_mem_rsv(of_flat_tree);
>>> + int j;
>>> +
>>> + /* Look for the dummy entry and delete it */
>>> + for (j = 0; j < total; j++) {
>>> + fdt_get_mem_rsv(of_flat_tree, j, &addr, &size);
>>> + if (addr == rd_data_start) {
>>> + fdt_del_mem_rsv(of_flat_tree, j);
>>> + break;
>>> + }
>>> + }
>>
>> ...and the above loop and delete will then be unnecessary.
>
> Again, protected by initrd_start/_end being non-zero.

My point is to pass in 0,0 *so that* they are not created at all, rather
than passing in dummy values, creating entries that we have to
delete/rewrite later.

>>> + ret = fdt_add_mem_rsv(of_flat_tree, initrd_start,
>>> + initrd_end - initrd_start + 1);
>>> + if (ret < 0) {
>>> + printf("fdt_chosen: %s\n", fdt_strerror(ret));
>>> + do_reset (cmdtp, flag, argc, argv);
>>> + }
>>> +
>>> + do_fixup_by_path_u32(of_flat_tree, "/chosen",
>>> + "linux,initrd-start", initrd_start, 0);
>>> + do_fixup_by_path_u32(of_flat_tree, "/chosen",
>>> + "linux,initrd-end", initrd_end, 0);
>>> + }
>>> +#endif
>>> debug ("## Transferring control to Linux (at address %08lx) ...\n",
>>> (ulong)kernel);
>>
>> ...and you will have to pass in '1' for the create (last) parameter in
>> the do_fixup_by_path_u32() calls to create them if they don't exist.
>
> They should exist by the time we are doing the fixup.
>
>> Is that better, or just a different way to do the same thing? It
>> seems more straight-forward to me.
>
> Its just re-ordering the way we do things.
>
> - k

The patch is creating dummy initrd entries in the reserved map and in
/chosen, only to work hard to delete and re-create the reserved map
entries and rewrite the /chosen entries.

My counter-proposal is to not bother with dummy values. Simply pass in
0,0 which will prevent the creation of the initrd entries by
fdt_chosen(). By not creating dummy entries, you can simply create the
proper entries once you know what the the correct values are, rather
than the more complicated rsvmap search & delete + rsvmap creation +
/chosen modifications.

Best regards,
gvb