Commentary for Pesachim 79:10

The Sages taught: One may not soak barley in water on Passover. And if one did soak barley grain and it split, it is prohibited. If it did not split, it is permitted. Rabbi Yosei says: he should soak it in vinegar, and the vinegar will cause the grain to contract. However, Shmuel said: The halakha in not in accordance with the opinion of Rabbi Yosei. Rav Ḥisda said that Mar Ukva said: the prohibition does not apply only if it actually split. Rather, this is referring even to a case where if the barley grains were placed on a barrel of wine they would split by themselves. Rabenu Tam learned that it is referring to the top of an Avuv. Shmuel said: This halakha applies only if it actually split. Shmuel took action in accordance with his ruling, when he was in the village of bar Ḥashu’s house. He prohibited only barley grains that had actually split. And since the ruling was not decided, in favour of Mar Ukva or Shmuel, we rule stringently according to Mar Ukva, for this is a Torah doubt. And this is so regarding eating this grain, but if they are found in cooked food, and they are unsplit, since chametz prohibition for very small amounts is rabbinical, we do not forbid the cooked food, because of the two or three grains, unless they are split, like Shmuel, for it is now a rabbinical doubt and we are lenient. And there are those who say that the ruling is according to Shmuel, for Mar Ukva was Shmuel's student, and we don't rule according to the student in the presence of the teacher. And furthermore, we see that Shmuel acted on his ruling, and if it was not so, he would not have acted on it. And it seems to me that for sure, if the grains are found in the dough or in the matzah after it is baked that it is permitted if they did not split. And even if they split, it seems to me that it is permitted, for split grain is not chametz, but close to becoming chametz...

There are those who are surprised at Rashi for such leniency that permitsn dough that a gentile kneaded without supervision for we should be concerned that perhaps he kneaded it with leaven and so they explain the Gemara is referring to a case where the gentile kneaded the dough under supervision. This does not seem correct to me for otherwise the text should have been explicit and stated "the dough of gentiles kneaded under supervision." Therefore I prefer to follow Rashi that since we see no yeast or cracks it should be allowed.