On 17/01/2019 08:43, Roger Pau Monné wrote: > On Wed, Jan 16, 2019 at 07:51:33PM +0000, Andrew Cooper wrote: >> On 16/01/2019 11:52, Jan Beulich wrote: >>>>>> On 16.01.19 at 10:00, <andrew.coop...@citrix.com> wrote: >>>> --- a/docs/misc/xen-command-line.pandoc >>>> +++ b/docs/misc/xen-command-line.pandoc >>>> @@ -636,61 +636,83 @@ trace feature is only enabled in debugging builds of >>>> Xen. >>>> >>>> Specify the bit width of the DMA heap. >>>> >>>> -### dom0 (x86) >>>> -> `= List of [ pvh | shadow | verbose ]` >>>> +### dom0 >>>> + = List of [ pvh=<bool>, shadow=<bool>, verbose=<bool> ] >>>> >>>> -> Sub-options: >>>> + Applicability: x86 >>>> >>>> -> `pvh` >>>> +Controls for how dom0 is constructed on x86 systems. >>>> >>>> -> Default: `false` >>>> +* The `pvh` boolean controls whether dom0 is constructed as a PV or a >>>> PVH >>>> + guest. The default is PV. In addition, the following requirements >>>> must >>>> + be met: >>>> >>>> -Flag that makes a dom0 boot in PVHv2 mode. >>>> + * The dom0 kernel selected by the boot loader must be capable of the >>>> + selected mode. >>>> + * For a PV dom0, Xen must have been compiled with `CONFIG_PV` >>>> enabled. >>>> + * For a PVH dom0, Xen must have been compiled with `CONFIG_HVM` >>>> enabled, >>>> + and the hardware must have VT-x/SVM extensions available. >>>> >>>> -> `shadow` >>>> +* The `shadow` boolean is only applicable when dom0 is constructed as a >>>> PVH >>>> + guest, and controls whether dom0 uses hardware assisted paging, or >>>> shadow >>>> + paging. The default is HAP when available, and shadow otherwise. >>>> >>>> -> Default: `false` >>>> + This option is unavailable when `CONFIG_SHADOW_PAGING` is compiled >>>> out. A >>>> + PVH dom0 cannot be used if `CONFIG_SHADOW_PAGING` is compiled out, >>>> and the >>>> + hardware is not HAP-capable. >>> As mentioned elsewhere, I object to adding CONFIG_* into this doc, >>> which is intended to be meaningful to non-developers. But not to the >>> degree of NAK-ing the whole thing, if everyone else disagrees with me. >> I'm not sure what else to say. I object to purposefully omitting >> relevant information from our documentation. > Maybe it would be helpful to add some kind of tag that could > standardize the relationship between Kconfig options and command line > options? > > Kconfig: SHADOW_PAGING > > Or similar. This would get the specific Kconfig details out of the > general description of the functionality, thus not harming readability > by non-expert users? > > Using such tag would require some explanation of it's meaning at the > top of the document. > >> Most people reading it, including non-developers, will know what Kconfig >> is and how to check, owing to at least a basic knowledge of Linux. >> Those that don't will be capable of basic human interaction such as >> asking a question of someone more knowledgeable. > If the above is not suitable, I might suggest to reword the sentence > as: > > "This option is unavailable when the Kconfig `SHADOW_PAGING` option is > not selected at build time." > > Explicitly mentioning Kconfig and selected simplifies the language for > non-expert users IMO, and makes it clear this is exclusively a build > time decision. Note I'm not a native speaker, so my sense of easier to > understand could be completely wrong.
I have a rewrite of the head of the document pending anyway which I hope to get sorted properly for 4.12 While having a Kconfig: section would probably be fine for ~80% of the simple cases, it doesn't work for this patch. I guess the root of the issue is that I do not believe that phrasing the information like this makes it harder for non-expert users read/comprehend, and there definitely are a group of readers for which this information is relevant. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
