From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53235) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1favBV-0003q2-JH for qemu-devel@nongnu.org; Wed, 04 Jul 2018 23:43:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1favBS-0005M9-Dh for qemu-devel@nongnu.org; Wed, 04 Jul 2018 23:43:57 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 05 Jul 2018 05:43:45 +0200 From: Sebastian Bauer In-Reply-To: <20180704210459.GH7451@localhost.localdomain> References: <20180704112859.20146-1-kraxel@redhat.com> <20180704185321.GZ7451@localhost.localdomain> <6a0aba7b46b168360fb291eaec769eb0@sebastianbauer.info> <20180704205206.GG7451@localhost.localdomain> <20180704210459.GH7451@localhost.localdomain> Message-ID: Subject: Re: [Qemu-devel] [PATCH] vga: make stdvga the global default List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: Gerd Hoffmann , qemu-devel@nongnu.org, Paolo Bonzini , Alexander Graf , Marcel Apfelbaum , Aleksandar Markovic , Aurelien Jarno , "Michael S. Tsirkin" , David Gibson , BALATON Zoltan , qemu-ppc@nongnu.org, Richard Henderson Am 2018-07-04 23:04, schrieb Eduardo Habkost: > On Wed, Jul 04, 2018 at 05:52:06PM -0300, Eduardo Habkost wrote: >> On Wed, Jul 04, 2018 at 10:21:19PM +0200, Sebastian Bauer wrote: >> > Am 2018-07-04 20:53, schrieb Eduardo Habkost: >> > > > mc->kvm_type = spapr_kvm_type; >> > > > machine_class_allow_dynamic_sysbus_dev(mc, >> > > > TYPE_SPAPR_PCI_HOST_BRIDGE); >> > > > mc->pci_allow_0_address = true; >> > > > diff --git a/vl.c b/vl.c >> > > > index 16b913f9d5..e60bf2d6cd 100644 >> > > > --- a/vl.c >> > > > +++ b/vl.c >> > > > @@ -4475,10 +4475,10 @@ int main(int argc, char **argv, char **envp) >> > > > if (default_vga) { >> > > > if (machine_class->default_display) { >> > > > vga_model = machine_class->default_display; >> > > > - } else if (vga_interface_available(VGA_CIRRUS)) { >> > > > - vga_model = "cirrus"; >> > > > } else if (vga_interface_available(VGA_STD)) { >> > > > vga_model = "std"; >> > > > + } else if (vga_interface_available(VGA_CIRRUS)) { >> > > > + vga_model = "cirrus"; >> > > >> > > If we don't make the machines above have default_display=NULL, we >> > > won't need this hunk, right? In either case, I suggest doing >> > > this change on a separate patch. >> > >> > An alternative would be to define the default always to VGA_STD if the >> > machine does not override it. This is from the observation that the majority >> > would chose std. Obviously, having default values always has pro and cons. I >> > would not consider it harmful here. >> >> That would be my preference: not having any machine with >> default_display==NULL. I just don't want to make this a >> requirement for fixing the current bug. >> >> > >> > Is there any configuration that includes VGA_CIRRUS but not VGA_STD? >> >> Not sure, I'll check. > > I couldn't find any: Thanks for checking! In that case, the VGA_CIRRUS branch in the above hunk will never be executed (for any current config) after the proposed patch. So that branch could be eliminated. I also checked the code, default values are used also for other fields in that struct (e.g., default_cpus). If default values are considered fragile, they must be changed as well in the middle term. However, given a solid documentation (which is currently missing for these fields) I still think that default values are acceptable. Note that there seems also be the possibility to set != NULL default values in the machine_class_init() function. Bye Sebastian