Re: [EXTERNAL][PATCH] mips/mips_malta: Allow more than 2G RAM

[Philippe Mathieu-Daudé]

On 3/2/20 10:22 PM, Aleksandar Markovic wrote:
> Forwarding this to Igor. Can you please give us your opinion, Igor, on this 
> proposal?

I'm not sure it is Igor area.

What need to be reviewed here is the GT64120 north bridge, which works 
very well with the default config, but is fragile when modifying it.

I'd be more confident with an acceptance test running memtester.

> ________________________________________
> From: Jiaxun Yang <address@hidden>
> Sent: Friday, February 28, 2020 4:26 AM
> To: address@hidden
> Cc: address@hidden; Aleksandar Markovic; Jiaxun Yang; Yunqiang Su
> Subject: [EXTERNAL][PATCH] mips/mips_malta: Allow more than 2G RAM
>
> When malta is coupled with MIPS64 cpu which have 64bit
> address space, it is possible to have more than 2G RAM.
>
> So we removed ram_size check and overwrite memory
> layout for these targets.
>
> Signed-off-by: Jiaxun Yang <address@hidden>
> Suggested-by: Yunqiang Su <address@hidden>
> ---
>   hw/mips/mips_malta.c | 24 ++++++++++++++++++------
>   1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/hw/mips/mips_malta.c b/hw/mips/mips_malta.c
> index 6e7ba9235d..de89cdcfc1 100644
> --- a/hw/mips/mips_malta.c
> +++ b/hw/mips/mips_malta.c
> @@ -98,7 +98,8 @@ typedef struct {
>   } MaltaState;
>
>   static struct _loaderparams {
> -    int ram_size, ram_low_size;
> +    unsigned int ram_low_size;
> +    ram_addr_t ram_size;
>       const char *kernel_filename;
>       const char *kernel_cmdline;
>       const char *initrd_filename;
> @@ -1023,6 +1024,7 @@ static int64_t load_kernel(void)
>   {
>       int64_t kernel_entry, kernel_high, initrd_size;
>       long kernel_size;
> +    char mem_cmdline[128];
>       ram_addr_t initrd_offset;
>       int big_endian;
>       uint32_t *prom_buf;
> @@ -1099,20 +1101,28 @@ static int64_t load_kernel(void)
>       prom_buf = g_malloc(prom_size);
>
>       prom_set(prom_buf, prom_index++, "%s", loaderparams.kernel_filename);
> +
> +    /*
> +     * Always use cmdline to overwrite mem layout
> +     * as kernel may reject large emesize.
> +     */
> +    sprintf(&mem_cmdline[0],
> +        "mem=0x10000000@0x00000000 mem=0x%" PRIx64 "@0x90000000",
> +        loaderparams.ram_size - 0x10000000);
>       if (initrd_size > 0) {
>           prom_set(prom_buf, prom_index++,
> -                 "rd_start=0x%" PRIx64 " rd_size=%" PRId64 " %s",
> -                 xlate_to_kseg0(NULL, initrd_offset),
> +                 "%s rd_start=0x%" PRIx64 " rd_size=%" PRId64 " %s",
> +                 &mem_cmdline[0], xlate_to_kseg0(NULL, initrd_offset),
>                    initrd_size, loaderparams.kernel_cmdline);
>       } else {
> -        prom_set(prom_buf, prom_index++, "%s", loaderparams.kernel_cmdline);
> +        prom_set(prom_buf, prom_index++, "%s %s",&mem_cmdline[0] 
> ,loaderparams.kernel_cmdline);
>       }
>
>       prom_set(prom_buf, prom_index++, "memsize");
>       prom_set(prom_buf, prom_index++, "%u", loaderparams.ram_low_size);
>
>       prom_set(prom_buf, prom_index++, "ememsize");
> -    prom_set(prom_buf, prom_index++, "%u", loaderparams.ram_size);
> +    prom_set(prom_buf, prom_index++, "%lu", loaderparams.ram_size);
>
>       prom_set(prom_buf, prom_index++, "modetty0");
>       prom_set(prom_buf, prom_index++, "38400n8r");
> @@ -1253,12 +1263,14 @@ void mips_malta_init(MachineState *machine)
>       /* create CPU */
>       mips_create_cpu(machine, s, &cbus_irq, &i8259_irq);
>
> -    /* allocate RAM */
> +#ifdef TARGET_MIPS32
> +    /* MIPS32 won't accept more than 2GiB RAM due to limited address space */
>       if (ram_size > 2 * GiB) {
>           error_report("Too much memory for this machine: %" PRId64 "MB,"
>                        " maximum 2048MB", ram_size / MiB);
>           exit(1);
>       }
> +#endif
>
>       /* register RAM at high address where it is undisturbed by IO */
>       memory_region_add_subregion(system_memory, 0x80000000, machine->ram);
> --
> 2.25.1