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The fixed-size components field in SNDRV_CTL_IOCTL_CARD_INFO can be too small on systems with many audio devices. Keep the existing struct snd_ctl_card_info ABI intact and add a new ioctl SNDRV_CTL_IOCTL_CARD_BYTES that carries a variable-length payload selected by a type discriminator. The first defined type SND_CTL_CARD_BTYPE_COMPONENTS returns the full components string. The ioctl is designed to be reused for other variable-length card payloads in the future. The user-space caller may set data_allocated == 0 (or data == NULL) to query the required length; otherwise the kernel copies the payload into the user buffer and writes back the actual length in data_len. When the legacy components field in struct snd_ctl_card_info is truncated, '>' is written just before the NUL terminator to signal to user-space that the full string is available via the new ioctl. card->components is now dynamically allocated and grown in 32 byte increments via krealloc(), capped at 512 bytes. Link: https://github.com/alsa-project/alsa-lib/pull/494 Suggested-by: Jaroslav Kysela <perex@perex.cz> Suggested-by: Takashi Iwai <tiwai@suse.com> Signed-off-by: Maciej Strozek <mstrozek@opensource.cirrus.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> Link: https://patch.msgid.link/20260720103505.1860399-2-mstrozek@opensource.cirrus.com