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
[SeaBIOS] [PATCH 2/2] vgabios: Limit the range of the VBE number of "pages" parameter.
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. 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; +if (pages < 2) +pages++; SET_FARVAR(seg, info->mode_attributes, mode_attr); SET_FARVAR(seg, info->planes, planes); SET_FARVAR(seg, info->pages, pages - 1); -- 1.8.3.1 ___ SeaBIOS mailing list SeaBIOS@seabios.org http://www.seabios.org/mailman/listinfo/seabios
