Re: [PATCH 2/2] kconfig: Print the value of each reverse dependency

Ulf Magnusson
2018-02-13T06:18:33Z

On Tue, Feb 13, 2018 at 1:56 AM, Eugeniu Rosca <roscaeugeniu@gmail.com> wrote:
> From: Eugeniu Rosca <erosca@de.adit-jv.com>
>
> Assuming commit 617aebe6a97e ("Merge tag 'usercopy-v4.16-rc1' of
> git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux"), ARCH=arm64
> and vanilla arm64 defconfig, here is the top 10 CONFIG options with
> the highest amount of OR sub-expressions that make up the final
> "{Selected,Implied} by" reverse dependency expression.
>
> | Config | Revdep all | Revdep ![=n] |
> |-------------------------------|------------|--------------|
> | REGMAP_I2C | 212 | 9 |
> | CRC32 | 167 | 25 |
> | FW_LOADER | 128 | 5 |
> | MFD_CORE | 124 | 9 |
> | FB_CFB_IMAGEBLIT | 114 | 2 |
> | FB_CFB_COPYAREA | 111 | 2 |
> | FB_CFB_FILLRECT | 110 | 2 |
> | SND_PCM | 103 | 2 |
> | CRYPTO_HASH | 87 | 19 |
> | WATCHDOG_CORE | 86 | 6 |
>
> The story behind the above table is that the user needs to visually
> review/evaluate 212 expressions which *potentially* select REGMAP_I2C
> in order to identify the expressions which *actually* select REGMAP_I2C,
> for a particular ARCH and for a particular defconfig used.
>
> To make this experience smoother, transform the way reverse dependencies
> are displayed to the user from [1] to [2].
>
> [1] Before this commit
> Symbol: MTD_BLKDEVS [=y]
> ...
> Selected by:
> - MTD_BLOCK [=y] && MTD [=y] && BLOCK [=y]
> - MTD_BLOCK_RO [=n] && MTD [=y] && MTD_BLOCK [=y]!=y && BLOCK [=y]
> - FTL [=n] && MTD [=y] && BLOCK [=y]
> - NFTL [=n] && MTD [=y] && BLOCK [=y]
> - INFTL [=n] && MTD [=y] && BLOCK [=y]
> - RFD_FTL [=n] && MTD [=y] && BLOCK [=y]
> - SSFDC [=n] && MTD [=y] && BLOCK [=y]
> - SM_FTL [=n] && MTD [=y] && BLOCK [=y]
> - MTD_SWAP [=n] && MTD [=y] && SWAP [=y]
>
> [2] After this commit
> Symbol: MTD_BLKDEVS [=y]
> ...
> Selected by:
> - [y] MTD_BLOCK [=y] && MTD [=y] && BLOCK [=y]
> - [ ] MTD_BLOCK_RO [=n] && MTD [=y] && MTD_BLOCK [=y]!=y && BLOCK [=y]
> - [ ] FTL [=n] && MTD [=y] && BLOCK [=y]
> - [ ] NFTL [=n] && MTD [=y] && BLOCK [=y]
> - [ ] INFTL [=n] && MTD [=y] && BLOCK [=y]
> - [ ] RFD_FTL [=n] && MTD [=y] && BLOCK [=y]
> - [ ] SSFDC [=n] && MTD [=y] && BLOCK [=y]
> - [ ] SM_FTL [=n] && MTD [=y] && BLOCK [=y]
> - [ ] MTD_SWAP [=n] && MTD [=y] && SWAP [=y]
>
> This patch has been tested using a custom variant of zconfdump which
> prints the reverse dependencies for each config symbol.
>
> Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Suggested-by: Ulf Magnusson <ulfalizer@gmail.com>
> Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
> ---
> scripts/kconfig/expr.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
> index 0704bcdf4c78..173fc5b252d5 100644
> --- a/scripts/kconfig/expr.c
> +++ b/scripts/kconfig/expr.c
> @@ -1185,7 +1185,19 @@ expr_print_newline(struct expr *e,
> void *data,
> int prevtoken)
> {
> - fn(data, NULL, "\n - ");
> + switch (expr_calc_value(e)) {
> + case yes:
> + fn(data, NULL, "\n - [y] ");
> + break;
> + case mod:
> + fn(data, NULL, "\n - [m] ");
> + break;
> + case no:
> + fn(data, NULL, "\n - [ ] ");
> + break;
> + default:
> + break;

The default case is redundant. expr_calc_value() returns a

typedef enum tristate {
no, mod, yes
} tristate;

(There's a separate sym_get_string_value() that deals with "string
values" of symbols.)

> + }
> expr_print(e, fn, data, prevtoken);
> }
>
> --
> 2.16.1
>

Looks good to me otherwise. I still like that earlier sorting idea,
but this is a big improvement already.

Cheers,
Ulf