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charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Stat-Signature: m5qqq9c64bj1f77hhkg7e5sm8wquusxi X-Rspamd-Queue-Id: 4205E18000D X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1713457401-622017 X-HE-Meta: U2FsdGVkX1+NFEdQu6NQlemJpWFx+MahaJSYSAVnyS1ndwGnpTEW34YP0iMDApHZRd+42x+ywKIQgU2GdEBonplXVlRIvpE6AEMl1+CwRq1Z3XL0fOxeR0VHnwdvCJ1jwV+H/wYOX5/oYxW0cVW9dcPgZeILnwKnEsIrNMZWjzWtewYyVaCJjsMgTvCoPGMbXwKvCsmO6wawwyzI0LRcCSIAtluiEnOQd7W5FTquH+kg3KndePLSHECJ5n158RdYKdN1UDogWmmnwjyPS+Xh+ufa8lj2kgGkQvgycfEtHIauQ50TA8rpBlCtpUYXW5v1P6GYl6a+Rx7zcs6NEQYE1GJqpD9F8qLP9e+jGfUtsboOojnzDenigayIc4skq0Az58WCK3lyE9RZQjJW5zVE08X8B+1bKOAvl82mesJNCLuSEDd7K9/3USadcTb5rBukL3oQGghtPxU8wkAmbgaHzezpzlVwWzQZ5DKFWzje1il6cG83gHH542PnlRJdPPW7fk+Pdhb1KTjkHORpxiqxHggm7UUzjX5pYTgsdbqeAEEAuf3eAq8GM9JEt5QNMtqWIn0Viym2Qf2I1BIMhVA5FPfwFYAQwfzvyGMZ9p7c1SLA9NdnzgHhGo/kwnW/wgKJ+kZAOJ37NraHs/L9nfD2yZSMLz0HDOhHRN4gJCcV8842+3yQ3xsYswOQQcp7xeaLHhBRxBpp/3ftrtQugdec5H3q52StdNB3Yq2M3Zl5yZNsGuj306mEya+ROgYKrAx3qZTWawlWHX011siqDN+AG+tiGacv+Y/2blJMzUEgVOA54kDhjt/Khd7c6EII6UuoH4Yf3CYvk9ihVa/n61vfEvcIZiL2v9LZzwyX0nacYRTiu7qP2Lo714g0QKzkQVgtuvWc++rsThZnQv92LhKB6qRsXsM/VP/O4HyH/3lPNsn4WFjPNZA+Qz7SLdSe9iWHHT0irAESUkWjKXVcCLx 8UKjeDUc VIRe4QOtsEEzoOchlyDM9jRsf+wppQgYcmTyUx+NffJqQYx0GfGJui5E3+Zk7ZKddFuWAb6QOL86Jj2d5RNwDiUWqIyENR5FtR2ZOYhaTyamw+Cu0h6nX87yvSjAl5BNHtIq3cggdPrCUJkZZD5qmWYRwgqUT9N32DCzISbDdKMQqhnl7hB31fC73agfpEoYSdnbKrTqZP+vjSskFWvPob5VmkS2y6TE2Ri6W+xBG13rrI3nBWz935L9FtZJr8LFps20L7V6bu6BqNxk= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 18.04.24 15:17, Alice Ryhl wrote: > On Thu, Apr 18, 2024 at 3:02=E2=80=AFPM Benno Lossin wrote: >> >> On 18.04.24 10:59, Alice Ryhl wrote: >>> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs >>> index 8fad61268465..9c57c6c75553 100644 >>> --- a/rust/kernel/types.rs >>> +++ b/rust/kernel/types.rs >>> @@ -409,3 +409,67 @@ pub enum Either { >>> /// Constructs an instance of [`Either`] containing a value of ty= pe `R`. >>> Right(R), >>> } >>> + >>> +/// Types for which any bit pattern is valid. >>> +/// >>> +/// Not all types are valid for all values. For example, a `bool` must= be either zero or one, so >>> +/// reading arbitrary bytes into something that contains a `bool` is n= ot okay. >>> +/// >>> +/// It's okay for the type to have padding, as initializing those byte= s has no effect. >>> +/// >>> +/// # Safety >>> +/// >>> +/// All bit-patterns must be valid for this type. This type must not h= ave interior mutability. >> >> What is the reason for disallowing interior mutability here? I agree >> that it is necessary for `AsBytes`, but I don't think we need it here. >> For example it is fine to convert `u8` to `UnsafeCell`. Niches also >> should not be a problem, since eg `Option>>` >> already fails the "All bit-patterns must be valid for this type". >=20 > If T: FromBytes allows transmuting &[u8; size_of::] into &T, then > it would be a problem as you could then use it to modify the original > &[u8]. Ahh that makes a lot of sense. --=20 Cheers, Benno