lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Wed, 19 Dec 2012 13:04:08 +0100
From:	Paolo Bonzini <>
To:	Stefan Hajnoczi <>
Subject: Re: [PATCH v2 1/5] virtio: add functions for piecewise addition of

Il 19/12/2012 11:47, Stefan Hajnoczi ha scritto:
> On Tue, Dec 18, 2012 at 01:32:48PM +0100, Paolo Bonzini wrote:
>> +/**
>> + * virtqueue_start_buf - start building buffer for the other end
>> + * @vq: the struct virtqueue we're talking about.
>> + * @buf: a struct keeping the state of the buffer
>> + * @data: the token identifying the buffer.
>> + * @count: the number of buffers that will be added
> Perhaps count should be named count_bufs or num_bufs.


>> + * @count_sg: the number of sg lists that will be added
> What is the purpose of count_sg?

It is needed to decide whether to use an indirect or a direct buffer.
The idea is to avoid a memory allocation if the driver is providing us
with separate sg elements (under the assumption that they will be few).

Originally I wanted to use a mix of direct and indirect buffer (direct
if add_buf received a one-element scatterlist, otherwise indirect).  It
would have had the same effect, without having to specify count_sg in
advance.  The spec is not clear if that is allowed or not, but in the
end they do not work with either QEMU or vhost, so I chose this
alternative instead.


> Stefan

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists