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Mon, 27 Oct 2025 09:04:32 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 2c93NaA1/2jVQwAAD6G6ig (envelope-from ); Mon, 27 Oct 2025 09:04:32 +0000 Date: Mon, 27 Oct 2025 10:04:32 +0100 Message-ID: <87ikg03ecf.wl-tiwai@suse.de> From: Takashi Iwai To: Maciej Strozek Cc: Jaroslav Kysela , Takashi Iwai , alsa-devel@alsa-project.org, patches@opensource.cirrus.com, linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ALSA: sound: Increase max size of components field In-Reply-To: <318f2ed3-57e6-495c-a773-4a094a3784cb@perex.cz> References: <20251023092754.84095-1-mstrozek@opensource.cirrus.com> <318f2ed3-57e6-495c-a773-4a094a3784cb@perex.cz> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/27.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-Spamd-Result: default: False [-3.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCPT_COUNT_SEVEN(0.00)[7]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:mid] X-Spam-Flag: NO X-Spam-Score: -3.30 X-Spam-Level: On Thu, 23 Oct 2025 13:56:26 +0200, Jaroslav Kysela wrote: > > On 10/23/25 11:27, Maciej Strozek wrote: > > The components field of snd_card can run out of space in new systems which > > use many audio devices, hence increase its size to 256 bytes. > > > @@ -1069,7 +1069,7 @@ struct snd_ctl_card_info { > > unsigned char longname[80]; /* name + info text about soundcard */ > > unsigned char reserved_[16]; /* reserved for future (was ID of mixer) */ > > unsigned char mixername[80]; /* visual mixer identification */ > > - unsigned char components[128]; /* card components / fine identification, delimited with one space (AC97 etc..) */ > > + unsigned char components[256]; /* card components / fine identification, delimited with one space (AC97 etc..) */ > Unfortunately, this change will introduce kABI breakage (ioctl number > change - structure size). > > You can probably define another struct snd_ctl_card_info and > SNDRV_CTL_IOCTL_CARD_INFO and update alsa-lib to use it depending the > protocol version. > > Or, we may introduce a separate ioctl for the components string. The > stripped components string in struct snd_ctl_card_info may have a > special ASCII mark like '>' at the end of string specifying the > availability of the complete string through another ioctl. I would > prefer this solution. > > Also, the components string may be dynamic in the kernel structure > (pointer) to save some space. 256 bytes is not small number. As Jaroslav suggested, we need a different solution to keep the compatibility. My gut feeling is for the option to provide a new ioctl as it can be most straightforward, but we can discuss further which is the good choice. thanks, Takashi