[U-Boot] [PATCH v2 7/7] MIPS: bootm: Add support for Vcore III linux kernel
Gregory CLEMENT
gregory.clement at bootlin.com
Fri Nov 30 14:16:57 UTC 2018
Hi Daniel,
On dim., oct. 28 2018, Daniel Schwierzeck <daniel.schwierzeck at gmail.com> wrote:
> Hi Gregory,
>
> sorry for the late response.
>
> Am 09.10.18 um 13:58 schrieb Gregory CLEMENT:
>> The kernels built for the Vcore III linux kernel have different
>> expectation in the way the data were passed.
>>
>> Unlike with yamon, the command line is expected to be a single string
>> passed in argv[1]. An other expectation is that the arguments are located
>> in the cached address space.
>
> I'm still not convinced whether this patch is necessary. As far as I
> understand, you can boot a mainline kernel with the device-tree blob way
> or with the legacy way. The latter makes sense when booting a mainline
> kernel with Redboot. But what's the use case for booting a mainline
> kernel in mainline U-Boot in the legacy way? Do you still want to boot
> out-of-tree legacy kernels with mainline U-Boot?
Currently there is only redboot which is used , but there is already
mainline kernel in legacy format. The purpose of it, is to be able to
switch from reboot to u-Boot but still being able to boot the mainline
kernel currently used.
As a bonus it could also allow to boot old out of tree kernel, but I
don't think it is something planed.
>
> Apart from this is this single cmdline string specific to Redboot or
> only to Microsemi? The former would be acceptable for a generic patch to
Actually I don't know.
> emulate a Redboot interface (similar to the YAMON one). But this should
> be configurable for the user via Kconfig. You could enable this by
> default with an "imply MIPS_BOOT_CMDLINE_REDBOOT" in your SoC/board
> specific Kconfig part.
>
>>
>> However, like yamon, they expect that rd_start and rd_size was passed by
>> the bootloader in the command line of the kernel, and besides that it
>> also wait for the root=/dev/ram0.
>
> Who exactly needs "root=/dev/ram0"? Normally the generic MIPS setup code
> only needs "rd_start" and "rd_size" from cmdline respectively
> "linux,initrd-start" and "linux,initrd-end" from the device-tree blob.
If it is a problem I think that we can use a U-boot script to take care
of this value.
Gregory
>
>>
>> Signed-off-by: Gregory CLEMENT <gregory.clement at bootlin.com>
>> ---
>> arch/mips/lib/bootm.c | 77 ++++++++++++++++++++++++++++++++-----------
>> 1 file changed, 57 insertions(+), 20 deletions(-)
>>
>> diff --git a/arch/mips/lib/bootm.c b/arch/mips/lib/bootm.c
>> index deca5189e3..803d5e1de3 100644
>> --- a/arch/mips/lib/bootm.c
>> +++ b/arch/mips/lib/bootm.c
>> @@ -15,6 +15,11 @@ DECLARE_GLOBAL_DATA_PTR;
>> #define LINUX_MAX_ENVS 256
>> #define LINUX_MAX_ARGS 256
>>
>> +enum legacy_boot_type {
>> + LEGACY_BOOT_YAML,
>> + LEGACY_BOOT_VCORE,
>> +};
>> +
>> static int linux_argc;
>> static char **linux_argv;
>> static char *linux_argp;
>> @@ -44,22 +49,46 @@ void arch_lmb_reserve(struct lmb *lmb)
>> lmb_reserve(lmb, sp, gd->ram_top - sp);
>> }
>>
>> -static void linux_cmdline_init(void)
>> +static void linux_cmdline_init(enum legacy_boot_type boot_type)
>> {
>> + switch (boot_type) {
>> + /*
>> + * Vcore III linux kernels expect arguments in the cached
>> + * address space. They also expect the command line being a
>> + * single string in the first argument
>> + */
>> + case LEGACY_BOOT_VCORE:
>> + linux_argv = (char **)(gd->bd->bi_boot_params);
>> + linux_argp = (char *)(linux_argv + LINUX_MAX_ARGS);
>> + linux_argv[1] = linux_argp;
>> + break;
>> + case LEGACY_BOOT_YAML:
>> + /* fallthrough */
>> + default:
>> + linux_argv = (char **)UNCACHED_SDRAM(gd->bd->bi_boot_params);
>> + linux_argp = (char *)(linux_argv + LINUX_MAX_ARGS);
>> + }
>> linux_argc = 1;
>> - linux_argv = (char **)UNCACHED_SDRAM(gd->bd->bi_boot_params);
>> linux_argv[0] = 0;
>> - linux_argp = (char *)(linux_argv + LINUX_MAX_ARGS);
>> }
>>
>> -static void linux_cmdline_set(const char *value, size_t len)
>> +static void linux_cmdline_set(const char *value, size_t len,
>> + enum legacy_boot_type boot_type)
>> {
>> - linux_argv[linux_argc] = linux_argp;
>> memcpy(linux_argp, value, len);
>> - linux_argp[len] = 0;
>> -
>> + switch (boot_type) {
>> + case LEGACY_BOOT_VCORE:
>> + linux_argv[linux_argc] = linux_argp;
>> + linux_argp[len] = 0;
>> + linux_argc++;
>> + case LEGACY_BOOT_YAML:
>> + /* fallthrough */
>> + default:
>> + linux_argp[len] = ' ';
>> + linux_argp[len + 1] = 0;
>> + linux_argc = 2;
>> + }
>> linux_argp += len + 1;
>> - linux_argc++;
>> }
>>
>> static void linux_cmdline_dump(void)
>> @@ -73,12 +102,11 @@ static void linux_cmdline_dump(void)
>> debug(" arg %03d: %s\n", i, linux_argv[i]);
>> }
>>
>> -static void linux_cmdline_legacy(bootm_headers_t *images)
>> +static void linux_cmdline_legacy(bootm_headers_t *images,
>> + enum legacy_boot_type boot_type)
>> {
>> const char *bootargs, *next, *quote;
>> -
>> - linux_cmdline_init();
>> -
>> + linux_cmdline_init(boot_type);
>> bootargs = env_get("bootargs");
>> if (!bootargs)
>> return;
>> @@ -104,7 +132,7 @@ static void linux_cmdline_legacy(bootm_headers_t *images)
>> if (!next)
>> next = bootargs + strlen(bootargs);
>>
>> - linux_cmdline_set(bootargs, next - bootargs);
>> + linux_cmdline_set(bootargs, next - bootargs, boot_type);
>>
>> if (*next)
>> next++;
>> @@ -113,7 +141,8 @@ static void linux_cmdline_legacy(bootm_headers_t *images)
>> }
>> }
>>
>> -static void linux_cmdline_append(bootm_headers_t *images)
>> +static void linux_cmdline_append(bootm_headers_t *images,
>> + enum legacy_boot_type boot_type)
>> {
>> char buf[24];
>> ulong mem, rd_start, rd_size;
>> @@ -121,7 +150,7 @@ static void linux_cmdline_append(bootm_headers_t *images)
>> /* append mem */
>> mem = gd->ram_size >> 20;
>> sprintf(buf, "mem=%luM", mem);
>> - linux_cmdline_set(buf, strlen(buf));
>> + linux_cmdline_set(buf, strlen(buf), boot_type);
>>
>> /* append rd_start and rd_size */
>> rd_start = images->initrd_start;
>> @@ -129,9 +158,13 @@ static void linux_cmdline_append(bootm_headers_t *images)
>>
>> if (rd_size) {
>> sprintf(buf, "rd_start=0x%08lX", rd_start);
>> - linux_cmdline_set(buf, strlen(buf));
>> + linux_cmdline_set(buf, strlen(buf), boot_type);
>> sprintf(buf, "rd_size=0x%lX", rd_size);
>> - linux_cmdline_set(buf, strlen(buf));
>> + linux_cmdline_set(buf, strlen(buf), boot_type);
>> + if (boot_type == LEGACY_BOOT_VCORE) {
>> + sprintf(buf, "root=/dev/ram0");
>> + linux_cmdline_set(buf, strlen(buf), boot_type);
>> + }
>> }
>> }
>>
>> @@ -276,11 +309,15 @@ static void boot_prep_linux(bootm_headers_t *images)
>> boot_reloc_fdt(images);
>> boot_setup_fdt(images);
>> } else {
>> - if (CONFIG_IS_ENABLED(MIPS_BOOT_CMDLINE_LEGACY)) {
>> - linux_cmdline_legacy(images);
>> + if (CONFIG_IS_ENABLED(SOC_VCOREIII)) {
>> + linux_cmdline_legacy(images, LEGACY_BOOT_VCORE);
>> + linux_cmdline_append(images, LEGACY_BOOT_VCORE);
>> + linux_cmdline_dump();
>> + } else if (CONFIG_IS_ENABLED(MIPS_BOOT_CMDLINE_LEGACY)) {
>> + linux_cmdline_legacy(images, 0);
>>
>> if (!CONFIG_IS_ENABLED(MIPS_BOOT_ENV_LEGACY))
>> - linux_cmdline_append(images);
>> + linux_cmdline_append(images, LEGACY_BOOT_YAML);
>>
>> linux_cmdline_dump();
>> }
>>
>
> --
> - Daniel
>
--
Gregory Clement, Bootlin
Embedded Linux and Kernel engineering
http://bootlin.com
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