[SeaBIOS] [PATCH RFC 5/7] Add PMM memory allocation facilities for VGA option ROMs
Mark Marshall
Mark.Marshall at csr.com
Tue Dec 20 12:59:16 CET 2011
Hi.
This patch series looks very interesting to me.
This patch has been dropped from the V2 series?
According to the bits of the PCI spec that I can find,
the option ROM is copied into RAM which is left read-write
while the initialisation vector is called, and the RAM is
then set to read-only after this time. Does your VGA option
ROM use this feature? Do you know of any other's that do?
(This is in the V2.1 and V3.0 PCI spec's. Also in at least
the V3.0 PCI spec is says that the initialisation code is
run in "big real mode", with 4G segments, do you know of
any code that uses this feature?).
(I understand that you might be using PMM memory because
you want read-write memory at run time, so my comments
might not be of help, but you could at least store the
pointer to your block in the ROM. I have found some BIOSs
that do modify the ROM image in this way (another common
thing to store is the PCI BDF of the device, and the BAR
locations).)
Thanks for the good work,
MM
PS.
I'm interested in this because I wrote the OGP VGA BIOS
(in 16-bit x86 ASM), a while ago now. A choice made for
two reasons really: 1, I hadn't found SeaBIOS (And didn't
know quite how well you could get gcc to produce 16-bit
code), and 2, I really wanted to write a chunk of 16-bit
assembler (this was a hobby, not work, so I felt I could
make a crazy choice like that and get away with it).
If I get a free afternoon, I will try to convert that code
to use the SeaBIOS VGA framework. It's interesting to note
that we have both implemented features that are not in the
other's BIOS.
> -----Original Message-----
> From: seabios-bounces at seabios.org [mailto:seabios-bounces at seabios.org]
> On Behalf Of Julian Pidancet
> Sent: 16 December 2011 14:15
> To: seabios at seabios.org
> Cc: Julian Pidancet
> Subject: [SeaBIOS] [PATCH RFC 5/7] Add PMM memory allocation facilities
> for VGA option ROMs
>
> This patch implements a way for option ROMs to allocate some space
> using the bios PMM interface.
>
> Since the VGA option ROM is placed in read only memory, the only way to
> get memory to store global variables is either use the EBDA, or use the
> PMM if the BIOS supports it.
>
> This simple patchs adds only pmm_scan and pmm_allocate. The first one
> is used to scan the memory and find the PMM entry point, the second one
> is used to request the BIOS to allocate blocks of memory.
>
> The pmm_find and pmm_deallocate functions are yet to be implemented.
>
> Signed-off-by: Julian Pidancet <julian.pidancet at gmail.com>
> ---
> Makefile | 2 +-
> vgasrc/pmm.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
> vgasrc/pmm.h | 16 ++++++++++++++++
> 3 files changed, 67 insertions(+), 1 deletions(-) create mode 100644
> vgasrc/pmm.c create mode 100644 vgasrc/pmm.h
>
> diff --git a/Makefile b/Makefile
> index cb00958..1b8ba60 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -171,7 +171,7 @@ $(OUT)bios.bin.elf $(OUT)bios.bin: $(OUT)rom.o
> tools/checkrom.py
>
> # VGA src files
> SRCVGA=src/output.c src/util.c vgasrc/vga.c vgasrc/vgafb.c
> vgasrc/vgaio.c \
> - vgasrc/vgatables.c vgasrc/vgafonts.c vgasrc/clext.c
> + vgasrc/vgatables.c vgasrc/vgafonts.c vgasrc/clext.c
> vgasrc/pmm.c
>
> $(OUT)vgaccode.16.s: $(OUT)autoconf.h ; $(call whole-compile,
> $(CFLAGS16) -S -Isrc, $(SRCVGA),$@)
>
> diff --git a/vgasrc/pmm.c b/vgasrc/pmm.c new file mode 100644 index
> 0000000..1732149
> --- /dev/null
> +++ b/vgasrc/pmm.c
> @@ -0,0 +1,50 @@
> +#include "biosvar.h" // GET_GLOBAL
> +#include "util.h" // memset
> +
> +#define PMM_SIGNATURE 0x4d4d5024 // $PMM
> +
> +struct pmmheader {
> + u32 signature;
> + u8 version;
> + u8 length;
> + u8 checksum;
> + u16 entry_offset;
> + u16 entry_seg;
> + u8 reserved[5];
> +} PACKED;
> +
> +u32 pmm_allocate(u16 seg, u32 length, u32 handle, u16 flags) {
> + u16 ax, dx;
> +
> + asm volatile ("movw %2, %%es\n"
> + "pushw %3\n"
> + "pushl %4\n"
> + "pushl %5\n"
> + "pushw $0x0\n" /* PMM_ALLOCATE */
> + "lcallw *%%es:7\n"
> + "addw $12, %%sp\n"
> + : "=a"(ax), "=d"(dx)
> + : "r"(seg), "r"(flags), "r"(handle), "r"(length)
> + : "cc", "memory");
> +
> + return (dx << 16) | ax;
> +}
> +
> +u16 pmm_scan(void)
> +{
> + u16 seg;
> + struct pmmheader *hdr = (struct pmmheader *)0;
> +
> + for (seg = 0xe000; seg; seg++) {
> + u32 val = GET_FARVAR(seg, hdr->signature);
> +
> + if (val == PMM_SIGNATURE &&
> + !checksum_far(seg, hdr, GET_FARVAR(seg, hdr->length))) {
> + return seg;
> + }
> + }
> +
> + return 0;
> +}
> +
> diff --git a/vgasrc/pmm.h b/vgasrc/pmm.h new file mode 100644 index
> 0000000..f6479ad
> --- /dev/null
> +++ b/vgasrc/pmm.h
> @@ -0,0 +1,16 @@
> +#include "biosvar.h" // GET_GLOBAL
> +#include "util.h" // memset
> +
> +#define PMM_MEMORY_TYPE_INVALID (0 << 0)
> +#define PMM_MEMORY_TYPE_CONVENTION (1 << 0)
> +#define PMM_MEMORY_TYPE_EXTENDED (2 << 0)
> +
> +#define PMM_BLOCK_NOT_ALIGNED (0 << 2)
> +#define PMM_BLOCK_ALIGNED (1 << 2)
> +
> +/* Only in PCI FW spec: */
> +#define PMM_MEMORY_ATTR_TEMPORARY (0 << 3) #define
> +PMM_MEMORY_ATTR_PERMANENT (1 << 3)
> +
> +u32 pmm_allocate(u16 seg, u32 length, u32 handle, u16 flags);
> +u16 pmm_scan(void);
> --
> Julian Pidancet
>
>
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