On Sunday 21 October 2012 14:20:05 Marcin Slusarz wrote: > BTW, _ROM method from https://lkml.org/lkml/2012/10/21/11 multiplies length > by 8, so maybe we can read 32kB in one batch? > > Marcin
That holds for that specific model, but it is not standard (in ACPI). Ben Skeggs has a laptop (Lenovo?) W530 that allows you to read the whole VBIOS in one call (that means chunk size > 4KiB), but there is another machine where this does not work (https://bugs.freedesktop.org/show_bug.cgi?id=55948). That machine allows you to read lengths of 4 KiB only (the buffer size is hard-coded to 4096, the upper bound of the returned size). I'd say, stick to 4 KiB for the first read, then try to read the remaining VBIOS in one shot and finally fallback to reading in chunks of min(4096, bios- >size - i). That should give a count of least 512 bytes. On my machine the length is 0x7d which translates to exactly 64 KB (not KiB). After your patch in https://lkml.org/lkml/2012/10/20/150, "drm/nouveau/bios: attempt to fetch entire acpi rom image in one shot" could be improved to only read the unknown VBIOS: /* disobey the acpi spec - much faster on at least w530 ... */ - ret = nouveau_acpi_get_bios_chunk(bios->data, 0, bios->size); + ret = nouveau_acpi_get_bios_chunk(bios->data, 4096, bios->size - 4096); Peter _______________________________________________ Nouveau mailing list Nouveau@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/nouveau