Re: [SeaBIOS] [PATCH 2/2] vgabios: Limit the range of the VBE number of "pages" parameter.
On Sat, Sep 14, 2013 at 09:11:02AM +0200, Paul Menzel wrote: > Am Freitag, den 13.09.2013, 16:24 -0400 schrieb Kevin O'Connor: > > Looking at the output of other VGA BIOS implementations, it appears > > that the number of available video pages reported is always between 1 > > and 127. > > That is including 1 and 127, right? > > > Signed-off-by: Kevin O'Connor > > --- > > vgasrc/vbe.c | 4 > > 1 file changed, 4 insertions(+) > > > > diff --git a/vgasrc/vbe.c b/vgasrc/vbe.c > > index d962333..2c08736 100644 > > --- a/vgasrc/vbe.c > > +++ b/vgasrc/vbe.c > > @@ -144,6 +144,10 @@ vbe_104f01(struct bregs *regs) > > mode_attr |= VBE_MODE_ATTRIBUTE_LINEAR_FRAME_BUFFER_MODE; > > break; > > } > > +if (pages > 128) > > +pages = 128; > > As 1 gets subtracted (below in diff), in this case 127 is included. > > > +if (pages < 2) > > +pages++; > > Can pages be 0? If yes, it would be 0 again after substracting 1. Should > it be `pages = 1` instead of `pages++`? The goal was to report 0 if there isn't enough memory for even a single image. Ideally that would not happen in practice as it shouldn't even be presented as a valid video mode if there isn't enough memory for it. Otherwise, the goal is to report between 1-127 (inclusive) for the number of pages. So, if there is only enough ram for 1 image, then the code would report 1 (which means 2 images). If there is enough ram for more than 128 images, then the code would report 127 (which means 128). This is what the AMD VGABIOS appears to be doing. -Kevin ___ SeaBIOS mailing list SeaBIOS@seabios.org http://www.seabios.org/mailman/listinfo/seabios
Re: [SeaBIOS] [PATCH 2/2] vgabios: Limit the range of the VBE number of "pages" parameter.
Paul Menzel wrote: > > +if (pages < 2) > > +pages++; > > Can pages be 0? If yes, it would be 0 again after substracting 1. Should > it be `pages = 1` instead of `pages++`? pages=2; //Peter ___ SeaBIOS mailing list SeaBIOS@seabios.org http://www.seabios.org/mailman/listinfo/seabios
Re: [SeaBIOS] [PATCH 2/2] vgabios: Limit the range of the VBE number of "pages" parameter.
Am Freitag, den 13.09.2013, 16:24 -0400 schrieb Kevin O'Connor: > Looking at the output of other VGA BIOS implementations, it appears > that the number of available video pages reported is always between 1 > and 127. That is including 1 and 127, right? > Signed-off-by: Kevin O'Connor > --- > vgasrc/vbe.c | 4 > 1 file changed, 4 insertions(+) > > diff --git a/vgasrc/vbe.c b/vgasrc/vbe.c > index d962333..2c08736 100644 > --- a/vgasrc/vbe.c > +++ b/vgasrc/vbe.c > @@ -144,6 +144,10 @@ vbe_104f01(struct bregs *regs) > mode_attr |= VBE_MODE_ATTRIBUTE_LINEAR_FRAME_BUFFER_MODE; > break; > } > +if (pages > 128) > +pages = 128; As 1 gets subtracted (below in diff), in this case 127 is included. > +if (pages < 2) > +pages++; Can pages be 0? If yes, it would be 0 again after substracting 1. Should it be `pages = 1` instead of `pages++`? > SET_FARVAR(seg, info->mode_attributes, mode_attr); > SET_FARVAR(seg, info->planes, planes); > SET_FARVAR(seg, info->pages, pages - 1); Thanks, Paul signature.asc Description: This is a digitally signed message part ___ SeaBIOS mailing list SeaBIOS@seabios.org http://www.seabios.org/mailman/listinfo/seabios
