Re: git: e962b37bf0ff - main - bhyve: Do not enable PCI BAR decoding if a boot ROM is present

On Fri, Sep 06, 2024 at 09:37:45AM -0400, John Baldwin wrote:
> On 9/5/24 22:10, Shawn Webb wrote:
> > Hey Mark,
> > 
> > This commit seems to force me to now pass "-o pci.enable_bars=true" to
> > all my VMs on amd64. I wonder if that might be a POLA violation. I
> > didn't realize that I needed to set that until I bisected the src
> > tree, looking for the commit that broke bhyve for me.
> > 
> > Is changing the default here really worth it for amd64? If so, I'm
> > thinking this should be in both RELNOTES and UPDATING. I now have to
> > propigate re-enabling this across my entire infrastructure.
> > 
> > Thanks,
> 
> That should only be true if you are using an older UEFI firmware that did
> not program BARs.  Are you seeing this on stock FreeBSD, and which version
> of the UEFI ROM are you using?

Indeed, it'd be nice to see which bootcode and guest you're using.  I
had tested bhyveload, edk2-bhyve and grub2-bhyve with this change
without problems, and wasn't planning to MFC.  My hope was that this
wouldn't have any user-visible impact on amd64, but if that's not the
case, the default for pci.enable_bars may have to be flipped on amd64.