Sender: Guenter Roeck <groeck7@gmail.com>
Message-ID: <e9d2baf8-4a70-313d-eebe-f0e4d1646971@roeck-us.net>
Date:   Mon, 13 Feb 2023 15:25:05 -0800
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.4.2
Content-Language: en-US
To:     David Howells <dhowells@redhat.com>
Cc:     Jens Axboe <axboe@kernel.dk>, Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>,
        Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
        Jeff Layton <jlayton@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        Hillf Danton <hdanton@sina.com>, linux-fsdevel@vger.kernel.org,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Christoph Hellwig <hch@lst.de>,
        John Hubbard <jhubbard@nvidia.com>
References: <55e2bef1-e8b5-3475-21df-487bddb47f5b@roeck-us.net>
 <20230213180632.GA368628@roeck-us.net>
 <20230209102954.528942-1-dhowells@redhat.com>
 <20230209102954.528942-4-dhowells@redhat.com>
 <2416073.1676328192@warthog.procyon.org.uk>
 <2451113.1676329970@warthog.procyon.org.uk>
From:   Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH v13 03/12] splice: Do splice read from a buffered file
 without using ITER_PIPE
In-Reply-To: <2451113.1676329970@warthog.procyon.org.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 2/13/23 15:12, David Howells wrote:
> Guenter Roeck <linux@roeck-us.net> wrote:
> 
>> Both are initrd.
> 
> Do you mean rootfs?  And, if so, is that tmpfs-based or ramfs-based?
> 

Both are provided to the kernel using the -initrd qemu option,
which usually means that the address/location is passed to the kernel
through either a register or a data structure. I have not really paid
much attention to what the kernel is doing with that information.
It is in cpio format, so it must be decompressed, but I don't know how
it is actually handled (nor why this doesn't fail on other boots
from initrd).

Guenter