Re: [PATCH v3] cmd: mem: add function for getting ram size for use in scripts

[Frank Wunderlich]

Hi Simon

Thanks for your review.

Am 4. Februar 2026 01:23:24 MEZ schrieb Simon Glass <sjg at chromium.org>:
>Hi Frank,
>
>On Sun, 18 Jan 2026 at 10:43, Frank Wunderlich <linux at fw-web.de> wrote:
>>
>> From: Frank Wunderlich <frank-w at public-files.de>
>>
>> Add a command for getting detected ram size with possibility to write
>> to environment variable.
>>
>> example usage:
>>
>> BPI-R4> msize
>> 4294967296
>> BPI-R4> msize m
>> 4096m
>> BPI-R4> msize g
>> 4g
>> BPI-R4> msize g ramsize
>> BPI-R4> printenv ramsize
>> ramsize=4
>> BPI-R4>
>>
>> board with 8GB ram:
>>
>> BPI-R4> msize
>> 8589934592
>> BPI-R4> msize m
>> 8192m
>> BPI-R4> msize g
>> 8g
>> BPI-R4> msize g ramsize
>> BPI-R4> printenv ramsize
>> ramsize=8
>> BPI-R4>
>>
>> Signed-off-by: Frank Wunderlich <frank-w at public-files.de>
>> ---
>> v2: add Kconfig entry
>> ---
>>  cmd/Kconfig |  5 +++++
>>  cmd/mem.c   | 32 ++++++++++++++++++++++++++++++++
>>  2 files changed, 37 insertions(+)
>
>Please can you add doc/usage/cmd/ and test/cmd

I already did in v6.

https://patchwork.ozlabs.org/project/uboot/patch/20260125131254.23210-2-linux@fw-web.de/

>>
>> diff --git a/cmd/Kconfig b/cmd/Kconfig
>> index 5c611fb3016e..b82b17195b7e 100644
>> --- a/cmd/Kconfig
>> +++ b/cmd/Kconfig
>> @@ -974,6 +974,11 @@ config CMD_RANDOM
>>         help
>>           random - fill memory with random data
>>
>> +config CMD_MEMSIZE
>> +       bool "memsize"
>> +       help
>> +         Get RAM via command for use in scripts.
>
>I suggest a little more info in your help, so it is clear what the
>command actually does.

Ok something like "print ram size in MiB or set environment variable with same value in decimal notation for use in scripts."

>> +
>>  config CMD_MEMTEST
>>         bool "memtest"
>>         help
>> diff --git a/cmd/mem.c b/cmd/mem.c
>> index d5d7ca2790bd..a067740d81c8 100644
>> --- a/cmd/mem.c
>> +++ b/cmd/mem.c
>> @@ -33,6 +33,7 @@
>>  #include <linux/compiler.h>
>>  #include <linux/ctype.h>
>>  #include <linux/delay.h>
>> +#include <linux/sizes.h>
>>
>>  DECLARE_GLOBAL_DATA_PTR;
>>
>> @@ -711,6 +712,29 @@ static int do_mem_loopw(struct cmd_tbl *cmdtp, int flag, int argc,
>>  }
>>  #endif /* CONFIG_LOOPW */
>>
>> +#ifdef CONFIG_CMD_MEMSIZE
>> +static int do_mem_size(struct cmd_tbl *cmdtp, int flag, int argc,
>> +                      char *const argv[])
>> +{
>> +       u64 memsize = gd->ram_size;
>> +
>> +       if (argc > 1) {
>> +               if (!strcmp(argv[1], "m"))
>> +                       memsize = (memsize + SZ_1M - 1) / SZ_1M;
>> +               else if (!strcmp(argv[1], "g"))
>> +                       memsize = (memsize + SZ_1G - 1) / SZ_1G;
>
>Can you do something like this?
>
>memsize = ALIGN(memsize, SZ_1G)

V6 only does MiB to make code more clear, avoid issues on round and also not needing floading point.

>> +               if (argc > 2)
>> +                       env_set_ulong(argv[2], memsize);
>
>Normally U-Boot uses hex, so it would be worth mentioning that this
>command doesn't. Or even provide a -d flag to select decimal?

I can mention that result is in decimal of course similar to help text above...seems i missed this in v6.

>> +               else
>> +                       printf("%lld%s\n", memsize, argv[1]);
>> +       } else {
>> +               printf("%lld\n", memsize);
>> +       }
>> +
>> +       return 0;
>> +}
>> +#endif /* CONFIG_CMD_MEMSIZE */
>> +
>>  #ifdef CONFIG_CMD_MEMTEST
>>  static ulong mem_test_alt(volatile ulong *buf, ulong start_addr, ulong end_addr,
>>                           volatile ulong *dummy)
>> @@ -1404,6 +1428,14 @@ U_BOOT_CMD(
>>  );
>>  #endif /* CONFIG_LOOPW */
>>
>> +#ifdef CONFIG_CMD_MEMSIZE
>> +U_BOOT_CMD(
>> +       msize,  3,      1,      do_mem_size,
>> +       "get detected ram size, optional set env variable with value",
>> +       "[m, g] [envvar]"
>> +);
>> +#endif /* CONFIG_CMD_MEMSIZE */
>> +
>>  #ifdef CONFIG_CMD_MEMTEST
>>  U_BOOT_CMD(
>>         mtest,  5,      1,      do_mem_mtest,
>> --
>> 2.43.0
>>
>
>Regards,
>Simon


regards Frank