Re: [PATCH] docs: Discourage users from using fwcfg

On Tue, Sep 08, 2020 at 10:17:08AM +0200, Laszlo Ersek wrote: > On 09/07/20 16:38, Daniel P. Berrangé wrote: >> On Mon, Sep 07, 2020 at 04:20:02PM +0200, Michal Privoznik wrote: >>> On 9/7/20 3:57 PM, Martin Kletzander wrote: >>>> On Mon, Sep 07, 2020 at 03:48:16PM +0200, Michal Privoznik wrote: >>>>> Even though this was brought up in upstream discussion [1] it >>>>> missed my patches: users should prefer <oemStrings/> over fwcfg. >>>>> The reason is that fwcfg is considered somewhat internal to QEMU >>>>> and it has limited number of slots and neither of these applies >>>>> to <oemStrings/>. >>>>> >>>>> While I'm at it, I'm fixing the example too (because it contains >>>>> incorrect element name) and clarifying sysfs/ exposure. >>>>> >>>>> 1: https://www.redhat.com/archives/libvir-list/2020-May/msg00957.html >>>>> >>>>> Reported-by: Laszlo Ersek <lersek(a)redhat.com&gt; >>>>> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; >>>>> --- >>>>> docs/formatdomain.rst | 14 +++++++++----- >>>>> 1 file changed, 9 insertions(+), 5 deletions(-) >>>>> >>> >>> >>>> It's nice that you say that, but people who would like to use fw_cfg for >>>> passing >>>> in a huge blob, which is saved in a file, will read this, go to >>>> <oemStrings/> >>>> and see that there is no way to pass a file as an input.  Should that be >>>> dealt >>>> with somehow?  Or would that be discouraged as well? >>> >>> Unfortunately, QEMU doesn't allow reading OEM strings from a file (at least >>> quick glance over hw/smbios/smbios.c doesn't show any signs it's allowed). >> >> Indeed, that is an RFE I've never got around to > > Yes, I remember that -- I remember that we discussed this, and also that > you didn't have time for it. Which is entirely justifiable; other stuff > has been (and continues to be) more important. > > For reference, here's the launchpad ticket that tracks the RFE for QEMU: > > https://bugs.launchpad.net/qemu/+bug/1826200 I spent some time today (more than expected in fact!) implementing this.... https://lists.gnu.org/archive/html/qemu-devel/2020-09/msg03023.html

I hit a possible EDK2 bug when SMBIOS 3.0 where it hangs when the size exceeds about 128 KB, but I don't intend to investigate it further.