From: Ian Jackson <Ian.Jackson@eu.citrix.com>
To: Juergen Gross <jgross@suse.com>
Cc: Wei Liu <wei.liu2@citrix.com>,
Ian Campbell <ian.campbell@citrix.com>,
George Dunlap <George.Dunlap@eu.citrix.com>,
Chun Yan Liu <cyliu@suse.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
Jim Fehlig <JFEHLIG@suse.com>, Simon Cao <caobosimon@gmail.com>
Subject: Re: [PATCH V6 3/7] libxl: add pvusb API
Date: Mon, 14 Sep 2015 12:12:11 +0100 [thread overview]
Message-ID: <22006.43915.2549.265495@mariner.uk.xensource.com> (raw)
In-Reply-To: <55F6A729.3080301@suse.com>
Juergen Gross writes ("Re: [Xen-devel] [PATCH V6 3/7] libxl: add pvusb API"):
> On 09/14/2015 12:36 PM, George Dunlap wrote:
> > Anyone want to look into the Linux source code to find out how big it
> > will allow busnum / devnum to grow?
>
> drivers/usb/core/hcd.c is using a bitmap to find the next bus number
> currently not in use. It's size is USB_MAXBUS which in turn has the
> value 64.
>
> choose_devnum() in drivers/usb/core/hub.c is doing a similar job for
> device numbers. Here the highest number supported is 127.
We are defining an API, which shouldn't involve this kind of
implementation-grobbling.
At an API level, it seems that this Linux busnum is not documented to
have any particular number or behaviour or range or anything. We
should use the biggest type we can use conveniently.
Do we need to worry that some bus might have 2^24 unplugs/plugs
(perhaps in some kind of software emulation) and that we need to use a
type which can hold a uint32_t or maybe even a uint64_t ?
Ian.
next prev parent reply other threads:[~2015-09-14 11:12 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-10 10:35 [PATCH V6 0/7] xen pvusb toolstack work Chunyan Liu
2015-08-10 10:35 ` [PATCH V6 1/7] libxl: export some functions for pvusb use Chunyan Liu
2015-08-11 11:26 ` Wei Liu
2015-08-10 10:35 ` [PATCH V6 2/7] libxl_read_file_contents: add new entry to read sysfs file Chunyan Liu
2015-08-11 11:26 ` Wei Liu
2015-08-12 2:37 ` Chun Yan Liu
2015-08-13 9:11 ` Wei Liu
2015-08-10 10:35 ` [PATCH V6 3/7] libxl: add pvusb API Chunyan Liu
2015-08-11 11:27 ` Wei Liu
2015-08-12 2:24 ` Chun Yan Liu
2015-08-13 9:09 ` Wei Liu
2015-08-14 1:49 ` Chun Yan Liu
2015-08-18 2:31 ` Chun Yan Liu
2015-08-31 6:10 ` Chun Yan Liu
2015-09-08 14:17 ` Ian Campbell
2015-09-08 16:52 ` George Dunlap
2015-09-09 7:38 ` Chun Yan Liu
2015-09-17 8:19 ` Chun Yan Liu
2015-09-17 9:54 ` George Dunlap
2015-09-29 17:19 ` Wei Liu
2015-09-17 8:20 ` Chun Yan Liu
2015-09-11 5:42 ` Chun Yan Liu
2015-09-11 13:26 ` Ian Campbell
2015-09-11 13:55 ` Juergen Gross
2015-09-11 14:09 ` Ian Campbell
2015-09-11 14:18 ` Juergen Gross
2015-09-11 14:41 ` Ian Campbell
2015-09-11 15:42 ` Ian Jackson
2015-09-14 3:48 ` Juergen Gross
2015-09-14 10:36 ` George Dunlap
2015-09-14 10:53 ` Juergen Gross
2015-09-14 11:12 ` Ian Jackson [this message]
2015-09-14 11:23 ` Juergen Gross
2015-09-14 14:03 ` George Dunlap
2015-09-17 8:24 ` Chun Yan Liu
2015-09-15 8:14 ` Chun Yan Liu
2015-08-10 10:35 ` [PATCH V6 4/7] libxl: add libxl_device_usb_assignable_list API Chunyan Liu
2015-08-10 10:35 ` [PATCH V6 5/7] xl: add pvusb commands Chunyan Liu
2015-08-10 10:35 ` [PATCH V6 6/7] xl: add usb-assignable-list command Chunyan Liu
2015-08-10 10:35 ` [PATCH V6 7/7] domcreate: support pvusb in configuration file Chunyan Liu
2015-08-11 11:27 ` Wei Liu
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