Hi Eugeniu,
> From: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
> Commit 1ccb27143360 ("kconfig: make "Selected by:" and "Implied by:"
> readable") made an incredible improvement in how reverse dependencies
> are perceived by the user, by breaking down the single (often
> interminable) expression string into small readable chunks.
> Even so, what happens in practice when reading the reverse
> dependencies is that 80-90% of the OR sub-expressions simply don't
> matter, since they evaluate to [=n].
> 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 30 of 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 |
> | IRQ_DOMAIN | 75 | 19 |
> | SERIAL_CORE | 75 | 9 |
> | PHYLIB | 74 | 16 |
> | REGMAP_MMIO | 72 | 15 |
> | GENERIC_PHY | 67 | 20 |
> | DMA_ENGINE | 66 | 11 |
> | SERIAL_CORE_CONSOLE | 64 | 9 |
> | CRYPTO_BLKCIPHER | 64 | 13 |
> | PINMUX | 60 | 17 |
> | CRYPTO | 59 | 10 |
> | MII | 58 | 8 |
> | GPIOLIB_IRQCHIP | 58 | 9 |
> | MFD_SYSCON | 58 | 15 |
> | VIDEOBUF2_DMA_CONTIG | 46 | 4 |
> | REGMAP_IRQ | 45 | 6 |
> | REGMAP_SPI | 44 | 2 |
> | CLKSRC_MMIO | 42 | 5 |
> | SND_SOC_GENERIC_DMAENGINE_PCM | 41 | 3 |
> | CRYPTO_SHA1 | 37 | 2 |
> | REGMAP | 36 | 4 |
> The story behind the above is that we still need 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.
> This patch attempts to bring at user's fingertips those reverse
> dependencies that actually participate in selection of given symbol
> filtering out the rest of them.
> Signed-off-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
> ---
> scripts/kconfig/expr.c | 24 +++++++++++++++++-------
> 1 file changed, 17 insertions(+), 7 deletions(-)
> diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
> index 2ba332b3fed7..147b2d8a8f3e 100644
> --- a/scripts/kconfig/expr.c
> +++ b/scripts/kconfig/expr.c
> @@ -1234,14 +1234,24 @@ static void __expr_print(struct expr *e, void (*fn)(void *, struct symbol *, con
> fn(data, e->right.sym, e->right.sym->name);
> break;
> case E_OR:
> - if (revdep && e->left.expr->type != E_OR)
> - fn(data, NULL, "\n - ");
> - __expr_print(e->left.expr, fn, data, E_OR, revdep);
> - if (revdep)
> - fn(data, NULL, "\n - ");
> - else
> + if (revdep) {
> + struct expr *left = e->left.expr;
> + struct expr *right = e->right.expr;
> +
> + if (expr_calc_value(left) != no) {
> + if (left->type != E_OR)
> + fn(data, NULL, "\n - ");
> + __expr_print(left, fn, data, E_OR, revdep);
> + }
> + if (expr_calc_value(right) != no) {
> + fn(data, NULL, "\n - ");
> + __expr_print(right, fn, data, E_OR, revdep);
> + }
> + } else {
> + __expr_print(e->left.expr, fn, data, E_OR, revdep);
> fn(data, NULL, " || ");
> - __expr_print(e->right.expr, fn, data, E_OR, revdep);
> + __expr_print(e->right.expr, fn, data, E_OR, revdep);
> + }
> break;
> case E_AND:
> expr_print(e->left.expr, fn, data, E_AND);
Thanks for trying to improve my change.
Applying your patch, running
$ ARCH=arm64 make defconfig && ARCH=arm64 make menuconfig
and searching for USB prints "Selected by:" with nothing actually selected.
Kind regards,
Petr
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