Re: [Xen-devel] [PATCH v2 5/6] xen: add /buildinfo/config entry to hypervisor filesystem

[Jürgen Groß <jgross@xxxxxxxx>]

On 13.11.19 15:12, Jan Beulich wrote:
> On 12.11.2019 17:45, Jürgen Groß wrote:
> > On 12.11.19 15:22, Jan Beulich wrote:
> > > On 02.10.2019 13:20, Juergen Gross wrote:
> > > > @@ -79,3 +80,11 @@ subdir-$(CONFIG_UBSAN) += ubsan
> > > >    
> > > >    subdir-$(CONFIG_NEEDS_LIBELF) += libelf
> > > >    subdir-$(CONFIG_HAS_DEVICE_TREE) += libfdt
> > > > +
> > > > +config_data.c: ../.config
> > > > +       ( echo "char xen_config_data[] ="; \
> > > > +         ../tools/bin2c <$<; \
> > > > +         echo ";" ) > $@
> > > Furthermore is there a reason to expose this as plain text, when
> > > Linux exposes a gzip-ed version in /proc? The file isn't very
> > > large now, but this was also the case for Linux many years ago.
> > gzip data may contain bytes with 0x00. Supporting that would require a
> > different interface at all levels.
> Then perhaps better do so now, when the code is still in flux, than
> after the fact, especially if "at all levels" is meant to also
> include the public interface?
I'll have a look into that.

> > > > --- a/xen/common/hypfs.c
> > > > +++ b/xen/common/hypfs.c
> > > > @@ -25,6 +25,10 @@ static struct hypfs_entry hypfs_root_entry = {
> > > >        .dir = &hypfs_root,
> > > >    };
> > > >    
> > > > +static struct hypfs_dir hypfs_buildinfo = {
> > > > +    .list = LIST_HEAD_INIT(hypfs_buildinfo.list),
> > > > +};
> > > > +
> > > >    static int hypfs_add_entry(struct hypfs_dir *parent, struct hypfs_entry *new)
> > > >    {
> > > >        int ret = -ENOENT;
> > > > @@ -316,3 +320,16 @@ long do_hypfs_op(unsigned int cmd,
> > > >    
> > > >        return ret;
> > > >    }
> > > > +
> > > > +static int __init hypfs_init(void)
> > > > +{
> > > > +    int ret;
> > > > +
> > > > +    ret = hypfs_new_dir(&hypfs_root, "buildinfo", &hypfs_buildinfo);
> > > > +    BUG_ON(ret);
> > > > +    ret = hypfs_new_entry_string(&hypfs_buildinfo, "config", xen_config_data);
> > > > +    BUG_ON(ret);
> > > > +
> > > > +    return 0;
> > > > +}
> > > > +__initcall(hypfs_init);
> > > Hmm, do you really want to centralize population of the file system
> > > here, rather than having the individual components take care of it?
> > I can add a new source, e.g. common/buildinfo.c if you like that better.
> I was rather thinking of moving this into common/kernel.c, next to the
> version hypercall handling, and together with exposing the suggested
> values here ahead of exposing .config.
Okay.


Juergen

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